L98 Stalling
Thread Starter
Melting Slicks
Joined: Apr 2004
Posts: 2,775
Likes: 138
From: cyberspace NY
L98 Stalling
my 89 just started stalling out when decelarting to an idle, like coming to a red light, or stop sign. Especially with the A/C on. It will start right back up again no problem; but I noticed it is idling low. like at about 600 rpm.
4 months ago I replaced the entire "top end". injectors, IAC, EGR, cap-rotor, IAT. There are NO codes being thrown.
Could it be my $50 autozone IAC crapped out ??
It also has a hesitation when cold that I could never find, but once in closed loop, she runs (ran) fine.
4 months ago I replaced the entire "top end". injectors, IAC, EGR, cap-rotor, IAT. There are NO codes being thrown.
Could it be my $50 autozone IAC crapped out ??
It also has a hesitation when cold that I could never find, but once in closed loop, she runs (ran) fine.
Instructor
Joined: Jul 2007
Posts: 222
Likes: 0
From: Toronto(Don Mills) Ontario
my 89 just started stalling out when decelarting to an idle, like coming to a red light, or stop sign. Especially with the A/C on. It will start right back up again no problem; but I noticed it is idling low. like at about 600 rpm.
4 months ago I replaced the entire "top end". injectors, IAC, EGR, cap-rotor, IAT. There are NO codes being thrown.
Could it be my $50 autozone IAC crapped out ??
It also has a hesitation when cold that I could never find, but once in closed loop, she runs (ran) fine.
4 months ago I replaced the entire "top end". injectors, IAC, EGR, cap-rotor, IAT. There are NO codes being thrown.
Could it be my $50 autozone IAC crapped out ??
It also has a hesitation when cold that I could never find, but once in closed loop, she runs (ran) fine.
Thread Starter
Melting Slicks
Joined: Apr 2004
Posts: 2,775
Likes: 138
From: cyberspace NY
ok, I took my used (but good) IAT sensor, and installed it as my coolant temp sensor. We'll see what happens.
It was stalling intermittently when hot, but that fixed itself. No explanation. No codes. just stopped happening.
Open loop still has major problems, runs terrible, bucking, hesitating, stumbling. But once it hits operating temp, she runs fine.
I can't figure this one out.
It was stalling intermittently when hot, but that fixed itself. No explanation. No codes. just stopped happening.
Open loop still has major problems, runs terrible, bucking, hesitating, stumbling. But once it hits operating temp, she runs fine.
I can't figure this one out.
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Joined: Oct 2007
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stalling
Unplug MAF sensor. Just fixed mine. 89 vert. No codes stalling. Unplugged MAF and worked fine. Then bought new MAF sensor. All is good now. Runs on MAF during open loop.
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Thread Starter
Melting Slicks
Joined: Apr 2004
Posts: 2,775
Likes: 138
From: cyberspace NY
Unplugged the MAF sensor, car ran worse, way worse. The CEL came on immediately, but it didn't run any better.
This TPI is too Finicky when cold. Low RPM's stumbling, hesitating, etc.
Once I get the RPM's up, it gets past the problem.
What sensors control the car when cold (Open loop) ??
I might spring for a new TB...
This TPI is too Finicky when cold. Low RPM's stumbling, hesitating, etc.
Once I get the RPM's up, it gets past the problem.
What sensors control the car when cold (Open loop) ??
I might spring for a new TB...
Instructor
Joined: Jul 2007
Posts: 222
Likes: 0
From: Toronto(Don Mills) Ontario
Unplugged the MAF sensor, car ran worse, way worse. The CEL came on immediately, but it didn't run any better.
This TPI is too Finicky when cold. Low RPM's stumbling, hesitating, etc.
Once I get the RPM's up, it gets past the problem.
What sensors control the car when cold (Open loop) ??
I might spring for a new TB...
This TPI is too Finicky when cold. Low RPM's stumbling, hesitating, etc.
Once I get the RPM's up, it gets past the problem.
What sensors control the car when cold (Open loop) ??
I might spring for a new TB...
Thread Starter
Melting Slicks
Joined: Apr 2004
Posts: 2,775
Likes: 138
From: cyberspace NY
Where can I get a fuel pump relay?
I can't find it at rockauto.com or napaonline.com
is it named something else ?
At this point I have no hesitations about replacing parts. Especially since everything is ~20 years old.
I can't find it at rockauto.com or napaonline.com
is it named something else ?
At this point I have no hesitations about replacing parts. Especially since everything is ~20 years old.
Instructor
Joined: Jul 2007
Posts: 222
Likes: 0
From: Toronto(Don Mills) Ontario
I dug out the old invoice from my Chev Dealer on the new F.P. Relay - it says it is/was #14078915(GM#?). Came in an ACDelco box - box label also said - Relay #212-307. Now this was for my 86 - I do not know for sure if your 89 uses the same Relay? Completely solved my problems, at least. Cost was approx $20.
- 1986 Original Owner -
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From: North Yorkshire, England
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
Relays rarely cause intermittent problems - bad connections do and though replacing a relay might lead to a cure, it's only because you've re-established the connection.
Instead of throwing money at parts, buy yourself a scanner and that will give you the clues you need to fix it. Fuel delivery, as previously mentioned, is controlled by the Coolant Temp Sensor Signal. Essentially, it takes the place of a Choke. All you've verified is that the Sensor is ok. You don't know if there's a wiring problem or the ECM could be bad and the only way to see what the ECM is seeing is with a scanner.
A few of us, including myself, had the ECM toggling this signal between 225 and 250 degrees, even when the motor was cold, so our Vettes didn't start or drive very well until the engine warmed up. The sensor was fine, the ECM wasn't. But I can't say that your Vette has that condition, because I've also experienced the loss of the a/c signal, which can lead to the driveability issues you've described. And there are other causes, which without some data, we can guess at and help you increase your supply of spare parts - or you can find out what's really going on and give yourself a much better shot of actually getting it fixed and your Vette back on the road.
Instead of throwing money at parts, buy yourself a scanner and that will give you the clues you need to fix it. Fuel delivery, as previously mentioned, is controlled by the Coolant Temp Sensor Signal. Essentially, it takes the place of a Choke. All you've verified is that the Sensor is ok. You don't know if there's a wiring problem or the ECM could be bad and the only way to see what the ECM is seeing is with a scanner.
A few of us, including myself, had the ECM toggling this signal between 225 and 250 degrees, even when the motor was cold, so our Vettes didn't start or drive very well until the engine warmed up. The sensor was fine, the ECM wasn't. But I can't say that your Vette has that condition, because I've also experienced the loss of the a/c signal, which can lead to the driveability issues you've described. And there are other causes, which without some data, we can guess at and help you increase your supply of spare parts - or you can find out what's really going on and give yourself a much better shot of actually getting it fixed and your Vette back on the road.
Race Director
Joined: Sep 2005
Posts: 10,878
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St. Jude Donor '07
Assuming you have performed the 'tape the fuel pressure guage to the windshield' test and all was well, I would suggest testing your pick up coil. They're ~ $40 at Orielly and can cause intermittent spark issues.
Also, 20 year old relays are suspect. Throw a hunnerd at replacing as many of them as you can. MAF, MAF Burnoff, Fuel Pressure, etc. Clean the connectors while you're there!
Also, 20 year old relays are suspect. Throw a hunnerd at replacing as many of them as you can. MAF, MAF Burnoff, Fuel Pressure, etc. Clean the connectors while you're there!
Thread Starter
Melting Slicks
Joined: Apr 2004
Posts: 2,775
Likes: 138
From: cyberspace NY
I really can't imagine it being the FP relay, since that would affect it hot and cold, but for $15 who cares. I have no problem throwing parts at the car. especially cheap parts that are 20 years old.
But $400 for a MAF is out of the question.
The new TB is on order, and well as some other cheap parts.
we shall see if I can get my friends $500 scanner next weekend.
Either way it's a PITA because I have to wait until the motor cools off.
But $400 for a MAF is out of the question.
The new TB is on order, and well as some other cheap parts.
we shall see if I can get my friends $500 scanner next weekend.
Either way it's a PITA because I have to wait until the motor cools off.
Pro
Joined: Nov 2006
Posts: 727
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From: Ocean City Maryland
