Help!! Stumble/Cut at 5000 RPM

[FLG]

Did you check the cps gap? And did you check the connector on the firewall I mentioned?

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[Purplehazedog]

I just checked the connector on the Firewall. And gaped the CPS to .040...... No luck. A buddy of mine says I should try to swap out the Distributor. What do you guys think?

[gath]

I had an issue with stumblling after 3000rpm for some time after warming up, changed a lot of stuff with no luck, until I put a new coolant temp sensor.

[EatsHondas]

A buddy of mine says I should try to swap out the Distributor. What do you guys think?

The rotor bolts to the cam gear directly. There is no distributor. The DME takes care of the ignition timing.

[saturnv7890]

The rotor bolts to the cam gear directly. There is no distributor. The DME takes care of the ignition timing.

But there is still a distributor for the sake of the spark getting to the right cylinder still? Unless this is a m42?


Anyways it might be worth it look for pitting on the distributor contacts if you haven't already.

[FLG]

No there is a cap and rotor. Which op has changed. Op have you confirmed fuel pressure?

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[Purplehazedog]

Is there an ignition module? On these cars? I'll check fuel pressure next.

[FLG]

Ignition is controlled by the dme.

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[Purplehazedog]

Can my timing be off? I have not touched it. But can it move?

[Kozworth]

the c191 is a ninja issue, its hard to really even see if the issue is there.

My friend had a c191 that looked fine, but where the wires met the male/female pins there was no connection. I would highly recommend just cutting the connector togather, and souldering in a custom one. Its easier then trying to trace back to the dme to ohm test the circuit.

[603Racing]

Do you have an air/fuel ratio gauge in that race car? Fuel pressure gauge? This data would be helpful.

Going to quote myself at the risk of being an ass.

Testing fuel pressure should be one of the first steps, can save time and money. It's doubtful that injectors are the cause since you're only seeing this problem at high RPM... unless you do not have the correct injectors. Even though you swapped TPS, I would test that as Jim recommended. You need to determine what is causing your symptoms before you try fixing it.

[Purplehazedog]

I'm calling a local shop in the morning to have them check the fuel pressure, Air, voltage etc..... I've been crazy busy at work.

[Purplehazedog]

I just put a fuel pressure gauge on the car and it is consistant during the stumble. The gauge didn't move when the car would cut out. I'm going to try a volt meter next

[jlevie]

If the fuel pressure remained constant during a stumble, the likely candidate then becomes a loss of timing data, a loss of injector or coil power, or a loss of injector firing signals.

Does the tachometer react by dropping during a stumble? That would be indicative of a loss of timing data and/or an interruption in DME power.

FYI: I had the same sort of problem on my first two SpecE30's. After numerous swaps of everything in the engine management system the third used harness finally worked, for a while before a short developed in the wiring to the ECT & temp gauge sensors. The car now has a brand new harness.

Ultimately the way I diagnosed the cause was with a battery power oscilloscope connected to the CPS input to the DME monitored by a passenger.

[Purplehazedog]

@Jlevie.... Yes the Tach goes crazy during the stumble. I do have some old wires around the temp sensors, my temp gauge just resently started turning on and off.

I think I have bad wiring somewhere and I bought a used 105K harness. I plan on swapping it out as soon as if arrives, Unless I can find the bug before the weekend.

I'm trying to find someone with a Oscilloscope here locally.