luizajeff

It's been a little while from the last thread I dropped in hopes of resolving a problem I'm having. I'm back again because I have not yet found the fix and wanted to throw it out again for more ideas and help (if available).

Problem: When hot (well warmed up) my engine is stalling. It starts first with bucking as a total loss of power or engine dies momentarily before kicking back to life a few times but eventually dieing. This only happens when I'm pulling from a stop, stepping on the gas, and or when driving at slower speeds in a low rpm range. The condition only shows up after the engine is well warmed up. Also, given about half and hour or so to cool, the engine will fire right back up and off I go until the engine warms back up and the problem comes out again.
Also, the trouble started several thousands miles after my last mod change. They are as listed on my signature.

I've taken time to consider and check or replace a number of things,
-Checked sensor voltage and switches (per PFC) and they appear normal or within spec., including TPS
-Replaced water thermosensor
-Replaced O2 sensor
-Replaced ignition cable (8mm) and cleaned / inspected spark plugs
-Tested ignition coils and w/in spec. (but I've ordered a new leading coil pack considering that a coil may be faulty even when resistance checks are good)
-Triple checked vacuum hoses along with new hoses in "rats" nest and most others easaly reached.
-Considering replacing both FPR and FPD but need some suggestions about good aftermarket or OEM replacement units (if my new coil doesn't fix issue).

I've done lots of research on web and this forum. Summer's coming and I really want to drive my car so if anyone has anything more to consider or add I would be grateful.

jd to rescue

iTrader: (3)

Have you checked your ground wire contacts? Poor ground contact can cause all kinds of anomolies. Heat soak, as when you get your engine warmed-up, can cause loose or poor contacts to fail all together. You have three contacts: passenger side firewall off of the UIM, driver's side fender wall below fuse box, and driver's side engine block just above the oil pan lip. Make sure they are all scuffed free of corrosion and tightened.

luizajeff

Thanx for the suggestion. I have all those points with added ground wires already. I will be checking the wire harness to the coils when I replace the leading and as many other wires as I can get to while I'm under there. My grounds are good though. Thanx.

mad_7tist

all that **** and no fp reading? are the pfc temp corrections right?

luizajeff

Well, unless I missed something on the Commander, until I install a fuel pressure gauge I can't read fuel pressure. Also, the PFC temp corrections were "stock" or the presets. Also I'd drivent the car for thousands of miles with the PFC in and no correction or adjusting of preset values and this was in hot CA. So I don't think it is the ECU. If my coil install dosen't fix issue I will be installing Fuel pressure gauge to help trouble shoot before I buy any other parts.

yellowbird

Did you check the Clutch switch?

RX7Wishing

i would replace the leading and trailing coils. they could be failing when hot. I have a used set that work fine with 30K miles on them ill sell you cheap. let me know.

BigAl65

There is also a fuel thermosensor that may have some bearing on this (since its a temperature related problem).....

luizajeff

-Clutch switch is good, replaced last year
-I have a new leading coil on the way but Ill continue to monitor knock levels if it fixes the problem, the trailing coils could be bad too.
-I've considered the fuel thermosensor too, and as of yet haven't pulled it because of the location and work but I'll do that when (and if) I install a fuel pressure gauge if the new coil doesn't work.
You all have good ideas and it never hurts to re-think the simple stuff too. Thanx for the input - it's why the forum exists.

mad_7tist

the fuel thermo is not at issue. the coolant temp sensor may be a little whacky giving you a colder reading than it is and thus making the car a bit to fat. do the coil and then look at the fp if you still have probs. you can look at the sensors data to see if it is off when the car is running poorly. no need to swap parts

wReX

iTrader: (6)

It kinda sounds like the cars timing might be going out of whack when it heats up. I would look into a faulty trigger sensor, maybe the wiring leading from the sensor to your ECU. The sensor may test fine under normal circumstances however as the engine bay heats up the sensor can sometimes go out of spec. Also, the trigger wheel itself may be bent.

Force13B

iTrader: (19)

What about your wiring harness for your injectors, wires could be old a brittle and when hot they could be sending the wrong signals. The other one i'm think of might be way off but on my sisters BMW the intake pipe got a crack in it, when it got warm it would expand and let out air and cause the car to shutter and turn off. I doubt that is it but just something that happend to me and drove me crazy. Good luck though man.

luizajeff

The water thermo sensor is rather new and with a new (good)connection. I do agree that wiring could be an issue. When I pull the UIM I'll be checking the hoses, as many wires as I can get to, the thermosensor on the fuel rail and air intake sensor as well just to double check. What is a "trigger" sensor? Where is it located or does it have another name? Thanx again.

Force13B

iTrader: (19)

http://www.fd3s.cc/howto/manuals/1993_Full_Manual.pdf
This may help you out, use Ctrl+F to find words for things your looking for.

luizajeff

Another thought. Could a bad cat (original stock 104k miles) cause this kind of problem?

potatochobit

iTrader: (1)

it could cause u to stall, but it would do that when the engine is cool or hot, due to restriction in the exhaust flow.

kontakt

Sorry for the res, but did you get your coil, and did that fix it? I have this exact problem with my FC, but additionally it will just die out at idle occasionally. A really strong battery seems to keep me going for a bit, but I'm still working out the actual problem.

RobTheBankz

Here you have one more whit the same problem ! I havent find the problem and it makes me crazy. Hope some one can get to the bottom of this.

stevemack

My car has also been having the same problem. Tri-Point Engineering is trying to figure out what is wrong with it as we speak. As soon as they figure out what is wrong with my car I'll post the results for others to see.