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Lh0 engine stalls when warm, erratic idle

Old 11-05-2018, 03:13 PM
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Car: Pontiac Firebird Formula
Engine: 3.1 LH0
Transmission: 700R4
Axle/Gears: Automatic
Lh0 engine stalls when warm, erratic idle

Ok, Ií m still trying to figure out this problem. Engine stalls when reaches 220F, I have to step the pedal to avoid engine to stall. Runs great when cold. I just measured injectors ohms, all on 12,6- 12,8. Only the FPR is still to be changed. Could be this the solution? Over months I changed distributor, wires, spark plugs, map sensor, EGR valve, TPS, IAC, ECM...
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Old 11-05-2018, 03:42 PM
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Car: 1976 Chevy K10
Engine: L98 350 TPI
Transmission: TH350
Re: Lh0 engine stalls when warm, erratic idle

We need more information on your vehicle before anyone can help you! Year, engine size, and a list of any modifications are a good start!
.
What makes you think that your fuel pressure regulator is bad? A bad FPR could definitely be your issue, but its best to do some diagnosis before performing repairs on your vehicle. I would recommend to verify that your fuel pressure is within spec.
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Old 11-06-2018, 01:04 AM
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Re: Lh0 engine stalls when warm, erratic idle

Oops, Ií m sorry! Here it is:

- 3.1 V6 Lh0 120000 miles
- 1990 Firebird
- replaced almost all sensors over the engine bay
- replaced ignition coil
- replaced fuel pump
- fuel pump relay (by the way, I think the car had a non factory anti-theft system, because I found the wires of the three relays on the firewall badly spliced and soldered)

In spite of this, I still have the stall problem. I have to set IAC or TPS? Has this something to do with?

Thank you guys!
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Old 11-08-2018, 09:07 PM
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Car: 91 Firebird/88 Firebird/91 Formula
Engine: V6 3.1/V8 5.0/V8 5.0
Transmission: 4L60/700R4/4L60
Axle/Gears: 3.23/2.73/2.73
Re: Lh0 engine stalls when warm, erratic idle

Disconnect the vacuum hose from the FPR, start the engine, and wait about a minute and a half. If fuel comes out of the FPR port replace the diaphragm, if not leave it alone.
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Old 11-09-2018, 03:23 AM
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Re: Lh0 engine stalls when warm, erratic idle

Ok, thank you! Ií ll try as soon as I can!
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Old 11-09-2018, 08:05 AM
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Re: Lh0 engine stalls when warm, erratic idle

The new FPR is just arrived, bought from Rockauto, the Standard one. I found some o-rings in the box, where do I have to place them?
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Old 11-09-2018, 12:13 PM
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Engine: L98 350 TPI
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Re: Lh0 engine stalls when warm, erratic idle

I replaced the FPR on my 350 tpi a few weeks ago, bought the part from NAPA and it came with a bunch of o-rings, didn't need any of them. I haven't had any issues. That being said, if you remove something that has an o-ring, it's good practice to replace it. I think that they include those thinking that you'll be taking apart the fuel rail. Now would be a good time to check/replace your fuel filter. Often times a clogged or old fuel filter is the cause of improper fuel pressure. Best of luck!
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Old 12-12-2018, 03:56 PM
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Re: Lh0 engine stalls when warm, erratic idle

Thank you ChevyK10! I replaced the FPR, now the engine runs much better, but occasionally stalls when I turn the wheel full left or right and when Reverse is engaged. Maybe a defective TCC solenoid?
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Old 12-12-2018, 04:54 PM
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Re: Lh0 engine stalls when warm, erratic idle

If you have disconnected the battery will need to do an idle learn. This is required on the 3.1l cars with an automatic. A search using my name as the author and a keyword should bring up a thread or two on it.

It also helps to clean the throttle body butterfly. The EGR really gunks it up.

RBob.
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Old 01-03-2019, 12:57 AM
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Re: Lh0 engine stalls when warm, erratic idle

Hi guys, happy 2019!

Just to let you know the car doesnít stall anymore when in Drive, thank you all for the suggestions! Iíve however noticed that, when in Overdrive, the engine stumbles and tries to stall like I never did the relearn procedure. How can I solve this?
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Old 02-27-2019, 08:24 AM
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Car: 1991 Camaro RS
Engine: 3.1
Re: Lh0 engine stalls when warm, erratic idle

I'm having a similar problem with my 91 3.1 Camaro. It won't heat up as much as yours before stalling but when started from cold after 7-8 minutes. After about 7 minutes, the idle starts to drop and the engine will rev up like it's trying to compensate but it can't seem to hold it steady and eventually stalls. All injectors reading 12 ohms. Tested fuel pressure last night and it held a constant 40 PSI. Vacuum at about 15 in. Would FPR be culprit for me as well or not since pressure seems to be steady? Any other sensors I should be looking at? Replaced ECM and TPS already. IAC fairly new as well.
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