89 Celebrity hard start when hot.

[Greg3600]

I have an 89 Celebrity, 2.8 Multiport FI with 49,000 miles that has a starting problem. I'll try to present this a a fashion that makes sense.
In general the car has a hot(?) start problem. Normally the car starts fine and runs great. After driving the car for an undetermined length of time (seems to be a heat problem so after getting the car to full operating temperature) and parking the car and waiting an undetermined length of time (so far it seems to be between 20 minutes and 1 hour aprox), then when I try to start the car it will start for two or three hits on the cylinders and then "huffs" to a stop. Subsequent attempts to start usually give the same result with the motor starting then giving a putt putt or two before it stops. This may continue for many tries, or at any time the car may start and run fine in which case you can shut off the ignition and restart without any problems, even driving a long distance without fail. I have had the engine go into the putt putt mode for several minutes then when you try to give it gas it dies. But it seems that once it is running you can shut the ignition off and restart at any time no matter how hot, but once it sits for some time it will be tough to start.

Now the time of failure (or recognizable difference in starts) seems to occur right at the time the car should change from preset start values to using the sensor data, I believe. The engine hits might begin a rise in rpm and as it settles you get the putts and then it shuts off, or on a good start at this time you hear a clean combustion, rpms come up and the motor is off and running.
My first impression was it ran out of gas. so I changed the fuel filter. Then I got a fuel pressure gauge and checked the pressure, around 38 to 44 pounds. Also I have changed the ECM(required prom swap), EST, IAC, MAP, Air Density Sensor(not a MAF). O2 sensor checked vac lines, cleaned throttle body added injector cleaner, checked for stuck EGR solenoid.
Through out it all it never has thrown an error code.
Now on a side note here, the cooling fan used to run all the time, but this changed when I changed the ECM, but now I notice that the engine gets very hot(about 230) before it turns on the cooling fan and during one of the hot spells it did throw a 45 error which I'm still concidering, it only happened once and has not repeated.
So to the point - Anyone had a similar problem? Any suggestions from anyone? I going to see about cleaning the EGR and check the purge canister then maybe move to a fuel pressure regulator or a fuel pump and I have read some intrigueing things about the Crank Position Sensor.
Any suggestions are appreciated.
This is hard to discribe so I hope what I have given is enough.

[tomj76]

Are you correct about the engine, that it's a 2.8L MFI? I have a 3.1L MFI, and I thought the smaller engine was only available in a TBI configuration.

My engine normally doesn't trigger the cooling fan until the temp gauge reads at least 240 F. Your engine seems consistent with that. I believe the service manual states a similar temperature, maybe even as much as 260 F.

As far as your real problem, I believe you've described a cold start problem, which sounds like it has something to do with the fuel/air ratios. However, it could instead be similar to a problem I once had in '95 or so. In my case, I could start the vehicle fine, but as soon as I touched the accelerator the engine would stall, but it would idle without any problems. After it warmed up it finally would be OK to drive.

It turned out that the problem was on the ECM, where when it was cold the input from the temperature sensor was not being detected, but after the inside of the car warmed enough the contact was made and the engine ran fine. Without the input from the sensor, the computer was defaulting to an extremely high temperature reading, something like 450 F, so the mixture was adjusted very lean except at idle. It would start OK (and could also be driven for a minute or two) since the ECM was in open loop mode at startup.

On my 3.1L, there are two temperature sensors. One operates the fan, while the other is used by the temperature gauge on the dash. I believe the computer uses the one connected to the temperature gauge, but I might be wrong about that. The one for the fan is next to the thermostat, while the other is on the head above the #5 cylinder (firewall side of the engine, nearest to the driver).

The MAF might need to be cleaned. If you're careful you can do that easily with a can of electronic cleaning fluid. Also, you might need to clean the EGR valves and valve seats.

I'll look in my service manual later to see if it indicates any potential causes of your problem.

[Greg3600]

Thanks for your reply Tomj76.
I was a little shakey on the description at the time, but it is deffinitly a hot problem. When I first start the car in the morning, it runs great, actually after cooling off it starts fine and if you start the car immediatly after parking it starts fine. After more experience with the problem I find it happens at two different times.
First if you let the car run until it reaches operating temp around 220, and maybe let the fan come on and then park. and come back in 15 to 20 minutes, when you start the car it fires a few times, stumbles and dies. It will do this several times or even alot, and then start and run fine. Okay I say I can live with this BUT (this was the first fail reported by my wife) after leaving a stop light or sign and your coming up to speed the engine just gives out. It does not die right away but goes into the same condition I believe that its in when it won't quite start. This feels just like someone pulled the fire out of, I mean it will be pulling fine and then nothing. It takes maybe ten seconds for the engine to finally die, if you give it throttle during that time it will die sooner. And this does not happen all the time but enough to be scary.
Now do't think I'm crazy and throwing a lot of money at this, I have owned two 87's prior to this so I have a lot of parts for this car around- but I have tried fuel pump, fuel filter, fuel regulator, injector cleaner and cleaned the injectors as best I could. Though the car never has a miss. I have changed the tps, iac, est, ecm, cps, map, air density sensor(it is not a maf) scoured throught the vacuum lines and the wiring harnesses, checked fuses and even put in an alternator. some parts were new because if your going in its not worth using old part. I have unplugged all sensors and controllers one by one looking to recreate or change the problem and have yet to do so.
A couple of things I have not tried is a new Cal-Pak ( I'm a little uncertain about getting a correct one) I did try the wrong prom(calpak) and it died on my while running, the knock sensor and Egr though I have unplugged them both and have had no effect. I can not find an oil pressure switch which controls the fuel pump on this motor though my book says there is one. I have marched the relays around to swap the fuel pump relay and I have drank alot of coffee. Still no help.
Through all of this I have improved the way the car runs and idles and I think I might see better mileage if it keeps running.
I think I'll take a couple of days and drink beer and think about were to go now.
Thanks TomJ for your info on the temp - oh I do have two temp sensors, unplugged them both did not help the problem and both gave temp sensor code.

[tomj76]

Sorry for the delay since I last responded. Have you made any headway on this?

There were two things that you said that stood out to me.

>It will do this several times or even alot, and then start and run fine.
Do you mean that you don't have to wait for it to cool off or any long period of time, just keep trying and eventually you'll get it to go?

>It takes maybe ten seconds for the engine to finally die, if you give it throttle during that time it will die sooner.
Giving it throttle opens the air flow into the manifold and dials up the TPS. The computer responds by increasing fuel from the injectors. If it stalls more quickly with the air flow open, one guess that I'd offer is that it's a fuel delivery problem... pump, filter, regulator, injectors, computer. Another, less likely guess is that it's a timing issue, but I'd expect it to keep running even if the timing was off as long as it wasn't too far off.

I see that you replaced the fuel pump, filter, regulator, cleaned the injectors, replaced the TPS, IAC, and ECM, so I'd guess it's not one of those. I hate to suggest this because it would be hard to track down, but could it be a wire, maybe partially broken or insulation worn through?

The fact that the problem is intermittent is going to making it's resolution difficult.