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Old 12-02-2017, 08:22 PM   #61
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2003 L-Series 3.0L Sedan
Default Re: hard starting 2001 SL1

Thanks for detailed descriptions of anyone's aftermarket scanner like Snap-On's MT2500. Another member describes his Autel the same way yours does when commanding a specific solenoid for testing. These scantools are a step up from every day readers like mine with nothing more than logging capabilities to capture freeze frame data for later viewing.

As it is, hard starting, P0401 and P0410 are three separate issues. All three have solutions when addressed separately and correctly, with or without scantools. I'm not sure why your car hasn't been cured of both error codes as they've been repeating errors in these forums with most members successfully repairing and eliminating them, especially in states requiring emissions inspection.

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Old 12-02-2017, 10:06 PM   #62
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Default Re: hard starting 2001 SL1

I think the answer is that mine has had marginal fuel pressure, but not enough to throw a lean code before, for ages, that I did not discover until it got bad enough to throw the lean code.

And the stuck oil control ring issue plagued it for years, before I found the simple fix earlier this year, it was so bad it started burning 20W50 quarts of oil in 200 miles, before I find a simple fix here for that based on old GM TSB.

Those two, likely lead to a higher volume of carbon fouling in the head, and thus blocking the ports that lead to throwing the 401 and 410 codes. The fixes worked but always eventually came back.

I am thinking of seafoming the beast, and maybe waterboarding it LOL. To clean out the carbon, then go through the standard 401 and 410 check list again. Including if needed, pulling the exh manifold to clean the tiny ports some sadistic maniac engineer menace put on these, LOL. And no, I was not the engineer that did it, LOL. But in the mean time I have new test toys that might give me more clues.

That MT-2500 is supper cheap on ebay right now as shops have been selling them to upgrade to the new ones from Snap-on. Got about $300 tied in what I bought, but it covers 1987-90 Renix jeeps (the real reason I bought one, huge live data time saver), OBD-I and OBD-II up 2001, with all the accessories I bought with mine. The manual is still online. For narrow use, like OBD-II Saturn, you can a rig for about $200 if you shop all the ebay sales.

Quote:
Originally Posted by fdryer View Post
Thanks for detailed descriptions of anyone's aftermarket scanner like Snap-On's MT2500. Another member describes his Autel the same way yours does when commanding a specific solenoid for testing. These scantools are a step up from every day readers like mine with nothing more than logging capabilities to capture freeze frame data for later viewing.

As it is, hard starting, P0401 and P0410 are three separate issues. All three have solutions when addressed separately and correctly, with or without scantools. I'm not sure why your car hasn't been cured of both error codes as they've been repeating errors in these forums with most members successfully repairing and eliminating them, especially in states requiring emissions inspection.

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Old 12-02-2017, 10:10 PM   #63
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Default Re: hard starting 2001 SL1

I only tied them together when I discovered fixing the lean code, lean issue with a new FPR suddenly had it running for over a week with out any 401 or 410 red CEL light MIL code!! But it did not last. The codes eventually returned. My question is still why did they vanish for a tank of gas and about 10 days, after putting in the new FPR that fixed the hard start and stopped the lean code.

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Thanks for detailed descriptions of anyone's aftermarket scanner like Snap-On's MT2500. Another member describes his Autel the same way yours does when commanding a specific solenoid for testing. These scantools are a step up from every day readers like mine with nothing more than logging capabilities to capture freeze frame data for later viewing.

As it is, hard starting, P0401 and P0410 are three separate issues. All three have solutions when addressed separately and correctly, with or without scantools. I'm not sure why your car hasn't been cured of both error codes as they've been repeating errors in these forums with most members successfully repairing and eliminating them, especially in states requiring emissions inspection.

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Old 12-02-2017, 11:19 PM   #64
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Default Re: hard starting 2001 SL1

As you know and learned over the years, everything is a compromise. Replacing the fpr to bring back missing pressure to correct hard starting may not be the answer to correcting the two error codes even when they stayed away for days. Nothing changed the basic oil consumption issues that decorated the exhaust side plumbing and feeding some back into the intake for egr/emissions. There are many variables going on in dynamic action and juggling various factors can sometimes give false indications of problems being solved. I'm guessing you inherited this scenario.

Did you check fuel pressures after some time passed to ensure pressures are where they should be?

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Old 12-02-2017, 11:52 PM   #65
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Default Re: hard starting 2001 SL1

Quote:
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Did you check fuel pressures after some time passed to ensure pressures are where they should be?
No, its been on my RoundToIt List. But it is on the list!!!
Since the engine always starts in a fraction of a second (and has not thrown the code again) which it never did in years, maybe since we bought it 9 years ago, I have not been a rush to retest it. But I have been closing attention to the fuel trims!!!!! Leading indicators of an FPR issue, low fuel pressure....

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Old 02-18-2018, 11:16 PM   #66
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Default Re: hard starting 2001 SL1

Well it did it again, wanted to start and run at about 200 rpm, but dies. It was hot restart after a >5 minute shopping trip. Giving it throttle, partial to WOT got the same results.

For the 4th time now in I guess 10 weeks, I had to disconnect the battery, drain the ECU memory and reconnect the battery to fix it. This was the second time it had nothing to with using the OBD II scanner to clear codes.

No idea yet what is causing it. This is not the original problem I started the post for. Those prior two problems were and are fixed, weak battery was first, then a bad check valve on the FPR.

After clearing the memory, it fires up in 0.5 seconds, and runs great. Have not had time to investigate it further.

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Old 02-19-2018, 11:24 AM   #67
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Default Re: hard starting 2001 SL1

Do the simple temperature test after the car sits 8 hours and see how close the IAT and ECT are to each other as well as they are to ambient temp.

Your hard warm start could be a dripping injector flooding the hot engine. Or a IAC starting to go bad.

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Old 02-19-2018, 01:50 PM   #68
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Default Re: hard starting 2001 SL1

Thanks. IAT and ECT are supper close and accurate. And if it was a bad temp sensor, it would/should be repeatable.

I tried using the WOT trick to clear any possible flooding while cranking, and try cracking open the throttle to see if the IAC was stuck closed.

If it was an injector, shorting out +/- battery cables (disconnected from the battery) like I did to fix it 4 times in about 3 months would not un-flood it or fix a bad temp sensor.

It would also not fix a stuck IAC.

It must be bad start up data / calcs in the ECU in my opinion, .... TPS sending out a random bad closed throttle number that gets stored in the ECU as a limit?

Is there a reset timer relay for positioning the IAC.

Random Dirt on the MAF that clears out once it is running?

If it was the IAC, why would disconnecting the battery and clearing the ECU stored history, like fuel trims, immediately fix it?

Quote:
Originally Posted by 1996SL11.9L View Post
Do the simple temperature test after the car sits 8 hours and see how close the IAT and ECT are to each other as well as they are to ambient temp.

Your hard warm start could be a dripping injector flooding the hot engine. Or a IAC starting to go bad.

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Old 02-19-2018, 04:34 PM   #69
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Default Re: hard starting 2001 SL1

When you disconnect the battery you force the PCM to recalibrate the IAC.

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Old 02-19-2018, 04:50 PM   #70
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Default Re: hard starting 2001 SL1

Quote:
Originally Posted by 1996SL11.9L View Post
When you disconnect the battery you force the PCM to recalibrate the IAC.
Same goes for re-calibrating the other sensors, like the TPS.

So are you saying that disconnecting the battery, clearing the memory, and then connecting the battery switching the power on, makes it immediately reset the IAC? If I recall, I do not think it had time to do that. I don't think I gave it time (Not sure, I forget), but I think I went straight to crank and it fired up in .5 seconds like it normally does now (since I replace the FPR last year).

Wish I had my Snap on MT-2500 brick at the time, I could have checked the ECU data when it kept trying to start and idle at 200 rpm, and died about 8 times, but I was 40 miles away at the time.

When I get a chance I will check all the sensors data. It may be time to pull the IAC and inspect it just for grins. For I suspect it is not the cause.

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Old 02-19-2018, 07:16 PM   #71
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Default Re: hard starting 2001 SL1

On my 02 I hear it for around 2 seconds as soon as I connect the battery. Or it's the only thing I can figure it's doing repowering. And the noise comes from the throttle body.

Do you stick the key in and emidatly go to start? I turn key to run to let the fuel pump cycle and the Baro get set. Then I tag the starter.

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Old 02-19-2018, 07:29 PM   #72
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Default Re: hard starting 2001 SL1

Thanks, I will check next time.

I use to have to wait for the dash lights to go off to crank it.

New FPR fixed that 9 year old problem.

Now I go straight to tagging the starter, and it fires up in .5 seconds like a beast. Except these 3-4 recent times. First 2 of them I screwed up the ECU memory clearing codes and turned the power off too soon to the engine before the ECU reset. The last to times were a whole new thing with her.

Waiting did not fix the <200 rpm idle/starts that invariably died every time.

Quote:
Originally Posted by 1996SL11.9L View Post
On my 02 I hear it for around 2 seconds as soon as I connect the battery. Or it's the only thing I can figure it's doing repowering. And the noise comes from the throttle body.

Do you stick the key in and emidatly go to start? I turn key to run to let the fuel pump cycle and the Baro get set. Then I tag the starter.

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Old 11-13-2018, 10:55 PM   #73
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Default Re: hard starting 2001 SL1

Well I have had 4 times now since October last year where the 2001 SL1 refused to run after starting. It started after I fixed the weak battery (replaced it) and 1-2 weeks later replaced the FF-FPR which solved several problems. Fuel pressure has been normal since then. No NEW codes in a year.

It goes like this. Cold start is perfect. Drive a short or long trip, no problem.
Park, shut it off, come back say 10-15 minutes later, starts, but barely runs, maybe 350 rpm, and dies. As many as 10 restarts, same thing. Never runs more than 1-2 seconds.

WOT crank, it tries to fire for a second, then just cranks, as it has no gas at WOT. Then I Try a normal start/crank again, same problem, fires up never gets over about 350 rpm, and dies. So it was not flooded. I tried to crack open the throttle while cranking, and even once it catches and tries to run at 250-350 rpm, but it just dies out.

4 times now, about 3 months apart each (it is a DD) I have fixed the problem by disconnecting the battery, and shorting the harness + and - cables for about 20 seconds.

I never seem to have the usual problems with anything. Its a curse for me LOL. But I do enjoy the challenge.

Has anyone got any clue what is getting fixed by clearing the ECU/PCM memory when I short the cables? I know it is clearing the memory and resetting computer to factory default, but I can find nothing new in the OBD-II scans that has changed that might give me a clue as to what this new cloaked Gremlin from deep space is doing to haunt my Saturn.

I am usually the one that figures this stuff out for others.

IIRC this is the thread where I brought this issue up last year when it first did it. Now it has done it twice in about 12 weeks. Last time 4 days ago.
--------------------------------------
Oh, and BTW we bought another Saturn, Ion-standard shift, I forget the year, been a busy 4 weeks...., and the jeep fleet took notice and stopped miss behaving, LOLOL.

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Old 11-13-2018, 11:07 PM   #74
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Default Re: hard starting 2001 SL1

Quote:
Originally Posted by 1996SL11.9L View Post
When you disconnect the battery you force the PCM to recalibrate the IAC.
What makes the IAC get out of calibration?

Why can't it re-calibrate during and up to or after 10 failed restarts?

Is it sign I should pull it and clean it and the port?

Never been done on this beast in 70,000 miles or even 150,000 miles that I know of going back two owners (including me). I know my jeep buddies are always cleaning theirs and blaming them for stuff, but rarely fixes their real issues (vacuum leaks...)

Thanks for the answer that might be my first real clue!!!

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Old 11-14-2018, 10:58 AM   #75
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Default Re: hard starting 2001 SL1

The iacv is a slave device. The feedback sensor results in position data the pcm needs to command it to move incrementally. The sole job of the iacv is to fine tune idle rpm for cold, warm, and electrical loads. No memory involved in the iacv since its just a pair of stepper motors, feedback position sensor and round pintle valve to control the supplemental air bypassing the partially closed throttle plate. A good way to test iacv function is to block off the port hole in front of the throttle plate with a warm idling engine.

At normal idle (650-850 room), blocking the bypass air port with a finger should result in dropping idle to around 500 rpm. This is the factory throttle stop screw setting of a partially open throttle without any supplemental air being fed from the blocked port in the throttle body. As soon as you remove your finger to unblock the bypass air port, idle should jump up immediately then settle back to electronically controlled idle rpm (650-850 rpm). When the bypass air port is blocked, the pcm detects the drop in rpm and attempts to retract the iacv to allow more air into the intake but the port is blocked. The pcm retracts the iacv fully without any effect until you remove your finger to unblock the port. The sudden inrush of air raises rpm too high and the pcm detects this. It commands the iacv to extend the valve to close off airflow until the engine returns to normal idle rpm. All occurring in less than a few seconds. If you perform this test with the same outcome, the iacv is operating as designed and the pcm is commanding the iacv correctly. No reset of iacv function occurs. As a slave, it moves by commands from three pcm.

There is another consideration with a member struggling with a faulty pcm - possible degradation of the pcm 5v circuit. One member has noticed his pcm 5v supply seems to be slow at bringing up 5 volts on a cold pcm/engine. 5v is instant after cycling the engine off then on. As a rule, 5v being generated usually comes from a voltage regulator taking 12v and dropping it to 5v. Solid state devices are instantaneous but this pcm is showing sluggish 5v generation behavior. It seems to affect starting and the pcm hasn't been replaced yet. That thread is still open without a resolution. Perhaps this may your symptom too of a 5v supply acting irregular and affecting pcm operation.

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Old 11-25-2018, 06:01 PM   #76
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Default Re: hard starting 2001 SL1

The problem is getting more frequent, 4 times in 6 weeks, but is still not an all the time event. Once again, the basic issue is a cold start requires no prime and fires up in 1 second from off to run (so the FPR is holding pressure for days if needed).

5-10 minutes of idle after a cold start, warm restart is immediate, no problem. Absolutely no cold, warm or hot running issues.

After a 10/15-60-90 minute drive (hot engine), a restart in about 5-15 minutes after shut down, it tries to run (cranking is not a problem, it starts) but the rpm gauge never gets over about 250 rpm, and dies in 1 second or less after cranking ends.

Only fix I have found is to disconnect the + Bat cable at the battery, ground it for 10 seconds, reconnect it, and it acts perfectly normal again after clearing all the KAM memory in the ECU.

No other issues have been found that might give a clue as to what is going on.

I already know how all this stuff works well enough to write a book, but this current issue has me stumped so far.

Looking for some ideas to try, I am, LOL.

fdryer, my issue is on a hot engine, not a cold engine. But thanks for the feedback, and idea!!!

I have on 1-2 occasions had to crank it at WOT to dry it out, but only after clearing the ECU memory did that work!

I suspect it is related to the IAC motor, but is it a Temp sensor-ECU parameter issue causing the IAC to parked in the wrong place, or a sticking when hot IAC motor?

Any common frequent issues??? Could a bad IAT temp sensor / data signal do this? How does the IAC know where to park the IAC for cold versus hot re-start, or does it matter? That is one thing I have always wondered about. Seems like it would set the IAC at different locations based on temp sensors on start up, but I have no proof of this???? I never found any proof of this, but I have never found any right ups on how the programs were set for this issue.

I guess the IAC could be sticking on reset only when the engine is hot (full operating temp) ???

But why would clearing the ECU memory immediately fix it?

Did someone mention a relay or timer involved in the IAC resest after shutting off the car?

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Old 11-25-2018, 06:18 PM   #77
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Default Re: hard starting 2001 SL1

Quote:
Originally Posted by 1996SL11.9L View Post
When you disconnect the battery you force the PCM to recalibrate the IAC.
How is it getting out of calibration in the first place?

It does not matter whether I crank it immediately or wait 5-10 seconds.

One think I am sure of, is it is not leaking fuel/flooding. It holds pressure better than most rigs I have seen ever since I replaced the FPR/filter assy.

Buy repeated starting attempts, let say 10 times for up 10 seconds each, and then wiping the PCM memory, does require one crank at WOT for 6-8 seconds to dry it out, before it will start normally.

Unfortunately I can not get scanner data with out the engine running using OBD-II (????) at least not with my OBD tools as I recall from last week?

I can on my old jeeps using my MT-2500 :-)

I am wondering if I can pull a fuse to wipe the PCM memory?

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Old 11-25-2018, 07:06 PM   #78
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Default Re: hard starting 2001 SL1

Whether pulling the pcm fuse or battery negative, they both do the same to remove power to the pcm to erase keep alive memory - stored emissions parameters as the engine runs to meet emissions minimums programmed in pcms. The emissions learned while driving an erased pcm is stored in memory and compared to default parameters in every pcm to meet EPA regulations for each model and year.

A copy of how the idle air control valve explains its operation.
Attached Files
File Type: pdf Idle Air Control Description.pdf (121.6 KB, 5 views)

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Old 11-25-2018, 07:54 PM   #79
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Default Re: hard starting 2001 SL1

Quote:
Originally Posted by fdryer View Post
Whether pulling the pcm fuse or battery negative, they both do the same to remove power to the pcm to erase keep alive memory - stored emissions parameters as the engine runs to meet emissions minimums programmed in pcms. The emissions learned while driving an erased pcm is stored in memory and compared to default parameters in every pcm to meet EPA regulations for each model and year.

A copy of how the idle air control valve explains its operation.
But is it the PCM A or B fuse? I seem to recall there is more than one? Under the dash or the hood?

Emissions parameters should have nothing to with starting that I know? IAC position memory, if it got stuck maybe?

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Old 11-25-2018, 08:07 PM   #80
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2001 SL1
Default Re: hard starting 2001 SL1

This is a hot engine restart problem, not a running problem. There was nothing about the IAC reset for starting the engine in the pdf. I am about ready to do something abhor, throw a new IAC at it. Just wish I knew what the PCM does and why (data algorithm wise) on shut down. My Renix era Jeeps have a B+ relay (till 1990) that times a shut down sequence for resetting the IAC.

Quote:
Originally Posted by fdryer View Post
Whether pulling the pcm fuse or battery negative, they both do the same to remove power to the pcm to erase keep alive memory - stored emissions parameters as the engine runs to meet emissions minimums programmed in pcms. The emissions learned while driving an erased pcm is stored in memory and compared to default parameters in every pcm to meet EPA regulations for each model and year.

A copy of how the idle air control valve explains its operation.

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