Ultraman wrote:
Providence.........Devine intervention.........


J/K......I was thinking back to your tour of America in Lauren thread......

Hope it is an easy fix....

1Fast04Vert wrote: Guess it wouldn't hurt to get the fuel filter changed. Any chance of water in the tank?

Matatk wrote: What are the characteristics when it stalls? Hunting idle, low idle, sputtering, etc.

Ultraman wrote: Have you ever replaced the fuel pump...?

j3studio wrote:

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1Fast04Vert wrote: Guess it wouldn't hurt to get the fuel filter changed. Any chance of water in the tank?

The fuel filter was changed about 15,000 miles ago, but that's a quick and easy fix. Water in the tank is always a possibility, but the car is parked indoors and I'm fairly trusting of my local gas station.

Ultraman wrote: Quote:

j3studio wrote:

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1Fast04Vert wrote: Guess it wouldn't hurt to get the fuel filter changed. Any chance of water in the tank?

The fuel filter was changed about 15,000 miles ago, but that's a quick and easy fix. Water in the tank is always a possibility, but the car is parked indoors and I'm fairly trusting of my local gas station.

If the tank is not kept full all the time while sitting condensation can form and that can be the source of the water in the gas. If you used stabil or other such gas stability products that can help. It can be a problem in areas of high humidity which I believe you qualify... My Dad was a pilot and would never store his plane without a full fuel tank...even overnight because of this issue.

j3studio wrote:

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Matatk wrote: What are the characteristics when it stalls? Hunting idle, low idle, sputtering, etc.

I'm not trying to be funny, but all of the above (maybe not so much of the sputtering). Only happens in gear (not in park), only when moving slowly (not when actually stopped). The engine will start to hunt around 500 RPM - if it drops below 450 RPM or so it will stall. This can happen very suddenly or with a lot of warning.

bogus wrote: I doubt the return filter is doing it... it won't stop fuel from being sent. Considering age, I would replace the oil pressure sensor switch and the fuel pump relay. This sounds like it could be electrical. Next time it happens, monitor voltage, it is moving about or nearly fixed? If the volts jump up, then the pump might be shutting off.

Matatk wrote:

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j3studio wrote:

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Matatk wrote: What are the characteristics when it stalls? Hunting idle, low idle, sputtering, etc.

I'm not trying to be funny, but all of the above (maybe not so much of the sputtering). Only happens in gear (not in park), only when moving slowly (not when actually stopped). The engine will start to hunt around 500 RPM - if it drops below 450 RPM or so it will stall. This can happen very suddenly or with a lot of warning.

I have watched my car on the tech 1 while it was fluctuating trying to find the ecm idle point. Unfortunately the computer is sometimes too slow to compensate. I would clean the IAC first before replacing any parts. If it were sputtering I would suspect fuel issue.

j3studio wrote:

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Ultraman wrote: Quote:

j3studio wrote:

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1Fast04Vert wrote: Guess it wouldn't hurt to get the fuel filter changed. Any chance of water in the tank?

The fuel filter was changed about 15,000 miles ago, but that's a quick and easy fix. Water in the tank is always a possibility, but the car is parked indoors and I'm fairly trusting of my local gas station.

If the tank is not kept full all the time while sitting condensation can form and that can be the source of the water in the gas. If you used stabil or other such gas stability products that can help. It can be a problem in areas of high humidity which I believe you qualify... My Dad was a pilot and would never store his plane without a full fuel tank...even overnight because of this issue.

It's certainly worth eliminating and I have some Stabil - would putting some in now (potentially after the fact) help?

Ultraman wrote: John, how long was Lauren sitting with the fuel in it? How much was in the tank? Did you put fresh fuel in on top of the older fuel? If so how much?

Fuel that has lost its umph is one thing water in the fuel is another. Unless it has sat a long time it will usually start and run even though the gas is stale. 30 days to 6 months is usually enough time for fuel to degrade.

Putting in Stabil in bad gas will not fix it. What I have read is there is no miricle ingrediant that will repair all water absorbtion or phase seperation of H2O from the fuel ... if that is what your problem is. I'd start with a new fuel filter and see if that helps. If it is poor quality fuel then it has to be drained and new fresh put in. Along with the Sta-bil if she is going to sit for awhile ...

The other guys probably know a lot more then I do on it ...

1Fast04Vert wrote: Not very likely, but another thought. There is a water drain under the lid and just aft of the fill cap. If it is clogged then rain/wash water can build up and eventually work it's way into the tank.

Woodstock wrote: No codes? I am surprised no one asked yet. An L98 hardly ever stalls without setting a code.

bogus wrote:
I still think the oil pressure switch is to blame...

Check the book, John, and look at the diagram for the fuel pump circuit and you will see what I mean.

bogus wrote:
I don't think it's in the tank...

I still think the oil pressure switch is to blame...

Check the book, John, and look at the diagram for the fuel pump circuit and you will see what I mean.

If you have questions, please feel free to call.

bogus wrote:
no... that switch works in parallel with the fuel pressure relay.

if the relay fails, the switch takes over.

j3studio wrote:

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Woodstock wrote: No codes? I am surprised no one asked yet. An L98 hardly ever stalls without setting a code.

No codes.

Matatk wrote:

I still think you need to check the IAC.

j3studio wrote:

3) Something I hadn't noticed before because I usually start driving pretty quickly after starting the car - I started the car and left it in park. It took about 10 minutes to transition from open loop to closed loop. In open loop, the idle hunted like crazy from about 575 to 725 RPM. Once it got to closed loop it settled into a 550 to 600 RPM range.

Matatk wrote:

You can check the remaining hoses with propane to see if the idle changes.

j3studio wrote:

Think good thoughts - I'm pulling the throttle body later this afternoon ...

bogus wrote:
You need remedial mechanics training... the part that says "fuck it, it's bolted on, how bad can this be" and dive in regardless of the consequences.

CentralCoaster wrote:

Do the brakes feel good, or a little bit stiff/wooden? A brake booster starting to leak can cause the idle to stumble as it loses vacuum, when coming to a stop sign or holding the brakes in drive.

CentralCoaster wrote:

The torque converter loads the engine a little in drive vs. park, so being in drive always exacerbates any unsteady idle.

CentralCoaster wrote:

My friend's L98 had a massive vacuum leak from his aftermarket intake and it would stumble and die at idle, yet idled nicely (albiet a little high) with the EST disconnected. So I guess the computer was trying to control spark advance based on some bad information.

My car doesn't have that return filter TSB done to it, I understand it was done to eliminate water hammer (fuel hammer) in the fuel lines on cold starts. A filter seems like a mickey mouse fix for it, but I guess it doubles as a line snubber/dampener. Just like how a flashlight doubles as a hammer. My fuel lines rattle sometimes.

You are probably overdue for a IAC cleaning and IAC/TPS calibration and base idle adjustment. If you are afraid of poking your TPS wire insulation with probes you can buy a little pigtail diagnostic harness to plug inline with it.

CentralCoaster wrote:

Another piece that has a major affect on drivability and idle and is easy to repair is the coolant temp sensor. You can test the ohms per the factory manual, or just replace it. I think it's the one in the front of the intake base next to the cold start temp switch. You can either check it while on the car (with it disconnected from ecm), and compare it to the dash sensor, or throw it in a pot on the stove and see what ohms it reads in boiling water.

CentralCoaster wrote:
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bogus wrote:
You need remedial mechanics training... the part that says "fuck it, it's bolted on, how bad can this be" and dive in regardless of the consequences.

Yeah, then you can have a LT1 swap in progress in your driveway for a few years. ;)

j3studio wrote:

In addition, I found that my circa 2011 JBWeld fix for the air cleaner housing has completely failed. I bought a new air cleaner assembly and will probably ask the long-suffering John Porter for some of his garage time.

bogus wrote:

you can mention ANY thing here ...

bogus wrote:
I will have to check my books, but there is a way to reset the IAC.