Renix Problems & cylinder not powering

[ptf18]

Ecomike: Ive contacted 5-90. Ive checked wiring til Im blue in the face. Had the Ecu out and apart. Found a transistor "blown" that is simalar to what MR_W (the Serbia fellow) found is his ECU.

 

[89xj]

could it be a bad cam position/stator/pickup coil? doesnt the cam sensor determine when to fire the injectors?

 

[winterbeater]

The crank position sensor (CKP) and cam position sensor (CMP) work together to fire the injectors which are fired by the ECU/PCM completing the ground circuit.

 

[outlander]

What causes this rare kind of failure inside the renix computer???

 

[5-90]

What causes this rare kind of failure inside the renix computer???

Could be that the transistor substrate finally gets overheated (even with a heat sink and an aluminum case, it's not well-ventilated,) could be due to quantum disturbances (similar to the trouble with SSDs,) or any of a number of factors.

Considering that the fuel injector drivers end up switching on and off with a frequency of a few milliseconds, and switch about an ampere and a half (all told - injector coil, conductor loss, connexion losses, ...) the fact that they last twenty-odd years is actually pretty damned good! Throw in the heat and dust they're usually exposed to, and you've got outstanding longevity for a hostile operating environment...

 

[Ecomike]

Could be that the transistor substrate finally gets overheated (even with a heat sink and an aluminum case, it's not well-ventilated,) could be due to quantum disturbances (similar to the trouble with SSDs,) or any of a number of factors.

Considering that the fuel injector drivers end up switching on and off with a frequency of a few milliseconds, and switch about an ampere and a half (all told - injector coil, conductor loss, connexion losses, ...) the fact that they last twenty-odd years is actually pretty damned good! Throw in the heat and dust they're usually exposed to, and you've got outstanding longevity for a hostile operating environment...

Well all that leaves as a cause is morphodite quantum electrons.

 

[5-90]

Well all that leaves as a cause is morphodite quantum electrons.

Good point - are there arrows along the outside of the insulation in the intended signal direction? Morphodite quantum electrons can only read signs on the outside of the wire jacket, or they get badly lost...

 

[Ecomike]

Good point - are there arrows along the outside of the insulation in the intended signal direction? Morphodite quantum electrons can only read signs on the outside of the wire jacket, or they get badly lost...

:roflmao:

 

[Bobby@Bullydog]

I wish someone would just let us know the secret to fixing this issue. im tired of having a heep on my hands
im gonna try to run a ground on mine tomorrow and see if i can get the injector to fire at idle that way.

 

[5-90]

I wish someone would just let us know the secret to fixing this issue. im tired of having a heep on my hands
im gonna try to run a ground on mine tomorrow and see if i can get the injector to fire at idle that way.

We'll keep workin' on ideas if you keep forkin' over information. The trouble with "troubleshooting by remote control" is that the normal, natural flow of thought is interrupted, and things get missed that way.

In case you were wondering, the "morphodite quantum electron" exchange I just had with Mike is/was a huge joke - mainly between us, I think...

 

[Ecomike]

In case you were wondering, the "morphodite quantum electron" exchange I just had with Mike is/was a huge joke - mainly between us, I think...

But then again, morphodite electrons are no joking matter, neither are gremlins and second cousin hooligans (LOL), when they get loose and start mucking about :banghead:in our jeeps thus taking the fun out of driving them.

Unless I am mistaken we solved this one? Bad transistor on Renix ECU board, right? Third known one out of millions?

 

[Ecomike]

I have the EXACT problem on my 96 with cyl #1 Its driving me crazy too
idles like crap but off of idle it runs great.
But on mine the noid light blinks just fine on all cylinders
I did the same Ford FI swap thinking a few injectors could be junk. NO fix either
Im right there with you on pulling your hair out

Have you checked compression, the spark plug for fouling, or a bad insulator (which grounds out the spark), or the plug wire to #1. I had the same problem, but with an 89. Mine turned out to be bad head gasket between 2 cylinders. Ran great except at idle.

Has to be a spark fuel or compression problem. You can use a spare spark plug to test for spark while cranking. Test the fuel injector and FI circuit the way the OP here did, and lastly run a compression test on cyl #1. Then go from there.

 

[ptf18]

Eco: I openned up the Renix ECU and found that one of the plastic supports for one of the transistors had melted. MR_W had found the same thing on his ECU board.

Ive since purchased another ECU..

I'll post back on my results.

 

[old_man]

If I remember correctly, the 88 model still had the C101 connector mounted on the firewall just above the brake booster. They are so notorious for connection problems that a service bulliten was issued telling the techs to cut out the connector and wire it up directly. The fuel injector lines run through that connector.

First try plugging and unplugging the connector to see if that helps.

When I built my stroker, I cut out the connector and wired it directly just to forstall any future problems.

I posted this before I read the previous post It sounds like one of your FI driver transistors overheated and probably died. Check the DC resistance on the injectors before installing another ECU. They should read about 16 ohms. From time to time several windings can short. A good transistor can drive it for a while, but longterm operation causes the transistor to overheat and die.

 

[Bobby@Bullydog]

Have you checked compression, the spark plug for fouling, or a bad insulator (which grounds out the spark), or the plug wire to #1. I had the same problem, but with an 89. Mine turned out to be bad head gasket between 2 cylinders. Ran great except at idle.

Has to be a spark fuel or compression problem. You can use a spare spark plug to test for spark while cranking. Test the fuel injector and FI circuit the way the OP here did, and lastly run a compression test on cyl #1. Then go from there.

its NOT a compression issue. I dont know why everyone surrounds around that one question but when you can pull an injector plug off and the idle does NOT change on that one cylinder....then you know its an injector not firing. Low compression would have an issue throughout the entire RPM range no matter what and so would a bad head gasket.
Im beginning to think its a grounding issue on the harness now. I have swapped ECMs with a friend and it didnt change a single thing.

 

[Ecomike]

its NOT a compression issue. I dont know why everyone surrounds around that one question but when you can pull an injector plug off and the idle does NOT change on that one cylinder....then you know its an injector not firing. Low compression would have an issue throughout the entire RPM range no matter what and so would a bad head gasket.
Im beginning to think its a grounding issue on the harness now. I have swapped ECMs with a friend and it didnt change a single thing.

You can have low compression on one cylinder. Can be caused by a fuel injector that stuck open and washed the oil down thus causing rapid cylinder wear and loss of compression on that cylinder, A single valve can leak, resulting in low compression, or a head gasket leak. These all tend to show up as a rough idle, and an engine that runs smoother at rpms above idle that makes one think it is something other than a compression problem.

I wasted weeks and $$s on a rough idle problem I was sure was not compression. I was sure it was injector, and plug wire related. Turned out it was not. It was rare head gasket failure that only leaked gases back and forth between two adjacent cylinders without any other signs of a head gasket problem.

In summary, your conclusion is not 100% right. It MIGHT be (there is no "you know" yet) an injector problem. It still might be a wiring, or spark problem, or a compression on that one cylinder problem, or several of these at the same time, unless you have run other tests to eliminate those other possibilities. Try swapping injectors, and do a compression test on that cylinder.

 

[Bobby@Bullydog]

You can have low compression on one cylinder. Can be caused by a fuel injector that stuck open and washed the oil down thus causing rapid cylinder wear and loss of compression on that cylinder, A single valve can leak, resulting in low compression, or a head gasket leak. These all tend to show up as a rough idle, and an engine that runs smoother at rpms above idle that makes one think it is something other than a compression problem.

I wasted weeks and $$s on a rough idle problem I was sure was not compression. I was sure it was injector, and plug wire related. Turned out it was not. It was rare head gasket failure that only leaked gases back and forth between two adjacent cylinders without any other signs of a head gasket problem.

In summary, your conclusion is not 100% right. It MIGHT be (there is no "you know" yet) an injector problem. It still might be a wiring, or spark problem, or a compression on that one cylinder problem, or several of these at the same time, unless you have run other tests to eliminate those other possibilities. Try swapping injectors, and do a compression test on that cylinder.

Ive already done a compression test and all cylinders are around 150-160. Its nearly got 200k on it so thats about right. and ive already put in another full set of 5.0 injectors and that changed nothing at all. Ive put in fresh plugs, swapped plugs around, has new cap, wires, rotor, no cracks in anything. This is why its frustrating.

 

[Ecomike]

Ive already done a compression test and all cylinders are around 150-160. Its nearly got 200k on it so thats about right. and ive already put in another full set of 5.0 injectors and that changed nothing at all. Ive put in fresh plugs, swapped plugs around, has new cap, wires, rotor, no cracks in anything. This is why its frustrating.

Ok, and I see its a 96, OBD-II. Have you tried a noid light to see if the problem injector is getting power? Have you tried the added ground wire yet?

 

[Bobby@Bullydog]

Ok, and I see its a 96, OBD-II. Have you tried a noid light to see if the problem injector is getting power? Have you tried the added ground wire yet?

I did the noid light first and its really odd because it will blink just like all the rest BUT the injector never fires at idle almost like it doesnt have enough voltage to operate the injector but enough to power the light. So thats why I thought i had a bad injector but that wasnt the case either and i havent done the ground yet, Ive been riding the bike to work lately and just havent had time to mess with it. I just keep checking back here in hopes of that magical post that tells me exactly what to do other than keep chasin my tail

 

[Ecomike]

I did the noid light first and its really odd because it will blink just like all the rest BUT the injector never fires at idle almost like it doesnt have enough voltage to operate the injector but enough to power the light. So thats why I thought i had a bad injector but that wasnt the case either and i havent done the ground yet, Ive been riding the bike to work lately and just havent had time to mess with it. I just keep checking back here in hopes of that magical post that tells me exactly what to do other than keep chasin my tail

At this point I would re do the noid light test and wiggle the light to see if the connection is loose, and swap a pair of injectors. Sometimes these things change while you are running tests, intermittent. Could be a problem with the end connector not making good contact all the time. Or it could be a defective brand new injector that happened to end up in the same cylinder (highly improbable, 1 in 6 chance) but once we eliminate the possible we must evaluate and assume the impossible is possible and happening!).

Also try wiggle the injector wires, wiring harness to see if the problem comes and goes, like an intermittent ground in the harness, or ...