Engine Issues

[Dfarkas]

Hello All,

I am new to the form so apologies for my lack of research. Last December my Grandfather sent me his 93 SHO with a 3.0 and 5 speed. I remember riding in this car when I was younger. The car is absolutely beautiful. Well he gave it to me because it has a few mechanical issues that need to be figured out and he didn't want the car sitting anymore. Any way long story short. When the engine is cold the car will start up and run just fine until the car reached operating temp and the cooling fans kick on. Once the car reaches operating temp it starts to miss fire and then the engine continues to run but in what I would call limp mode. If I turn it off it will not start until the car cools down. We cannot get any codes off of the engine. I have replace the crank sensor, cam sensor, and the ICM. I have no idea what to replace next to fix this issue, any help would be greatly appreciated.

V/R
Dan

 

[Irish Pride]

Try unplugging the MAF sensor and see if it runs any different. Unplugging the MAF will put it into a type of default mode.

Try replacing the DIS with a known good one. The DIS is the 2 plugged sensor mounted on the passenger side of the intake manifold. Is that what you are calling the ICM? If so, where did you get the replacement? I've had bad luck with part store units and only use Ford/Motorcraft ones. If it is faulty it can act normal when cold and then break down as it gets hot. This is what controls the Ignition on the car so could very easily be the problem. If you don't have a spare to try then wait for it to start acting up and then start tapping on it with the Plastic handle of a screwdriver or something similar. You might me able to get it to pop in and out by doing that.

How are you checking for codes? Is there a check engine light on? Have you verified the CEL is illuminating?

-Chad

 

[SHOdded]

Maintenance history, mileage, how long/where has it been sitting?

How to read codes (readers are unreliable):
http://wikisho.com/wiki/EEC_Self_Test_Procedure

Def read codes. Here is what the codes would mean:
http://wikisho.com/wiki/Three-digit_EEC_codes

Post a video of the flashes for us to verify.

Does it rev freely in N and sound good when it has not yet reached operating temperature?

 

[luigisho]

Codes for sure. If you can jumper it and not get anything, including all clear code, then there is something wrong in that area as well.

Chad's guesses were mine as well starting with MAF and DIS. However the codes can point the way. Air, fuel spark. Could be fuel delivery, sensor malfunction, processor malfunction grounding issue. You have to try and narrow it down with codes if you can. Otherwise you can throw a bunch of unnecessary parts at it and still be stuck.

 

[Dfarkas]

Try unplugging the MAF sensor and see if it runs any different. Unplugging the MAF will put it into a type of default mode.

Try replacing the DIS with a known good one. The DIS is the 2 plugged sensor mounted on the passenger side of the intake manifold. Is that what you are calling the ICM? If so, where did you get the replacement? I've had bad luck with part store units and only use Ford/Motorcraft ones. If it is faulty it can act normal when cold and then break down as it gets hot. This is what controls the Ignition on the car so could very easily be the problem. If you don't have a spare to try then wait for it to start acting up and then start tapping on it with the Plastic handle of a screwdriver or something similar. You might me able to get it to pop in and out by doing that.

How are you checking for codes? Is there a check engine light on? Have you verified the CEL is illuminating?

-Chad

My dad replaced what you are calling the DIC for me last month. He ordered it through rock auto. I don't know where we would find a known good one. My grandfather had it replace 4 years ago. What do you mean is the CEL illuminating? We are checking for codes but nothing sticks in the ECU when the fault happens. My dad has a OB1 code scanner and he has done the jumper method.

V/R
Dan

 

[Dfarkas]

Maintenance history, mileage, how long/where has it been sitting?

How to read codes (readers are unreliable):
http://wikisho.com/wiki/EEC_Self_Test_Procedure

Def read codes. Here is what the codes would mean:
http://wikisho.com/wiki/Three-digit_EEC_codes

Post a video of the flashes for us to verify.

Does it rev freely in N and sound good when it has not yet reached operating temperature?

The car has about 160K on it. My grandfather bought it in 94 and I have detail maintenance history dating back to the day that he purchased the car. It spent from 94 to 2018 in North Carolina, and now the car is in southern Arizona at my dads house due to me having limited space in Texas. We have tried to run the codes on the car and nothing comes up we have used a scanner and the jumper method. I will try to get my dad to take a video for me and I'll post it when he gets that done. When the car is cold it revs like no other sounds good and healthy. Just when it gets to operating temp and the cooling fans kick on is when it has its issue, and then when the car cools down it will start back up and be fine until it hits operating temp again.

V/R
Dan

 

[Dfarkas]

Codes for sure. If you can jumper it and not get anything, including all clear code, then there is something wrong in that area as well.

Chad's guesses were mine as well starting with MAF and DIS. However the codes can point the way. Air, fuel spark. Could be fuel delivery, sensor malfunction, processor malfunction grounding issue. You have to try and narrow it down with codes if you can. Otherwise you can throw a bunch of unnecessary parts at it and still be stuck.

If this were a grounding issues would anyone have schematic so we could chase all the grounds down and clean and tighten them up. We are at the point of being tired of throwing unnecessary expensive sensors at it.

V/R
Dan

 

[luigisho]

I don't blame you. Keep in mind--code readers for this OBDI model have been unreliable and the jumper is the best way to obtain them. You can video it and post it for others to review.

Also, some of the aftermarket parts have a spotty history of working very well and many of us have learned to use used original parts vs new aftermarket when necessary. That relay module may be one of them. I always got a used one when I replaced mine. Same with MAF, PCM, and a few others.

There are used factory repair manuals on ebay usually for cheap. The EVTM booklet has wiring diagrams, vacuum diagrams etc. and there is a SHO specific repair manual for engine and transmission usually posted for sale if you need one.

 

[sperold]

Check the water pump weep hole with a dentists mirror. Even a new crank position sensor does not like to get wet.

The warm - up time is long enough to get the sensor wet and start the timing errors, then after it quits, the down time of a warm engine dries up the sensor to the point where it runs ok again. Until the next time.

 

[SHOdded]

What speeds do you drive? Do the fans come on during highway speeds or during extended idling?

 

[Dirty Harry]

Does this always happen at the exact same time as when the cooling fans kick in?

 

[SHOrod]

In addition to considering the MAF and ICM I'd also suggest checking the fuel pressure when cold as well as when the issue begins to happen. Weak fuel pumps can struggle to provide sufficient pressure after they've been operating a while and can cause the car to not restart until they cool down. Maybe the system voltage drop when the cooling fans kick in is dropping the fuel pressure just enough to cause the rough running and lack of power.

-Rod

 

[Dfarkas]

What speeds do you drive? Do the fans come on during highway speeds or during extended idling?

I have yet to be able to drive the car. Ill start the car and let it warm up because I know that it has this issue and after about 10 mins is when this issue happens.

Dan

 

[Dfarkas]

Does this always happen at the exact same time as when the cooling fans kick in?

This happens every time when the fans kick on. After about 10 minutes of a warm up.

Dan

 

[Dfarkas]

In addition to considering the MAF and ICM I'd also suggest checking the fuel pressure when cold as well as when the issue begins to happen. Weak fuel pumps can struggle to provide sufficient pressure after they've been operating a while and can cause the car to not restart until they cool down. Maybe the system voltage drop when the cooling fans kick in is dropping the fuel pressure just enough to cause the rough running and lack of power.

-Rod

Okay Ill look at the fuel pressure.

 

[rubydist]

What are the codes? We can speculate until the next election, but if you give us the codes then we can actually help you.

 

[Rotor]

Like rubydist said, without codes it’s a needle in a haystack. Even with codes it’s still a haystack, but a smaller one.

From what’s here so far I’m leaning towards the CCRM. It’s got your fan and fuel delivery going through it and because of its location right above the radiator they are notorious for heat and vibration related problems.

I also understand the wrong temp thermostat can cause issues but I have no idea if that includes the symptoms you are experiencing.