I have a Sandrail that has an 02' ZZ4, Superram intake, Accel DFI. On last trip I started having issues with the engine cutting out.
As I roll on gas it would briefly cut off/stumble/miss, then back on. On other times, it would cut off all together until I let up on the gas pedal. Then it would be fine.
Next time I drove it, all was fine for a full day of duning.
Next ride, started intermittantly cutting out.
Seemed to happen mostly just off idle. Started to stumble at idle as well.
Changed fuel filter, no difference.

Thanks,
Wejaz28

 

Any thoughts?

 

Could be a lot of things. Need more info. I'd start with making sure your ignition system, plugs, cap, wires are up to snuff. Then check your fuel pressure. Schraeder valve on the fuel rail, tape the gauge to the windshield and see what it's doing when you're driving.

The sheer number of things that could cause an off idle stumble is staggering, but make sure the basics are working, then make sure you're getting fuel.

 

Since you're running DFI, can you run a datalog and see what's up?

 

you can sweep the tps to look for open spots. If your running multec injectors it could be caused bye shorting coil.

 

Good thoughts. Ill check those

Can I data log with the base(free) software?

 

You should be able to datalog with a communication cable hooked to the ecm. You would use the accel dfi software.

 

I just want to be part of this conversation, I also have a zz4 with a stock 92 tpi system. The car will go a good run a few days and other days after 30-40 minutes of driving the car will start to struggle and turn off. I usually just wait a 5-10 minutes and the car will be like nothing happen. I already change the fuel pump, fuel pressure regulator, injectors, new spark plug wires. I'm going to try and replace the distributor module next.

 

Sounds like a possiable ecm. Bye turning off the key your resetting it.
Just a FYI it’s gm service number 1227730. I wouldn’t think the icm or pu coil would be bad . Because your not resetting anything in the distributor bye turning the key off and back on. You might be able to wrap on the ecm case while this is happening to see if it straightenes out or starts to act up.

 

If your stating the engine runs good when it’s cold but is dying when warm. I would think it needs to be tuned. Or you cold use a adjustable fuel pressure regulator to increase fuel flow. I have tuned a tpi maf zz4 , 30#hr injectors worked great. Might have been overkill but after the injector constant was set in the tune I still had to add some fueling to get the blm (block learn mode) in order.

 

Well, hooked up laptop and there was a stored code “23” right there on the dash screen. “Low TPS voltage” .
swapped it out, recalibrated and loaded new file. Cars runs fine, but this is an intermittent problem.
If it’s not fixed, suppose it could be whatever sends voltage to tps.

 

The ecm send 5v ref to the tps. This is the grey wire to the tps, the feedback is blue. Sounds unrelated to the tps maybe injectors shorting out. Are they multecs ?

 

Don’t know injector make offhand. Do know they are 32lbs.
as far as TPS low voltage code, you don’t think that can cause the cut out issue?

 

The low tps might cause a cut out, multecs were factory injectors used in the late 80s until 92 on f-body’s.
I think msd injectors are multecs too. The coil windings short out over time.
You can ohm injectors warm to see if a coil is going bad.

 

If an injector was bad, wouldn't that injector cause one dead hole, other 7 still firing.
This problem manifests itself as a complete shut down if I continue to depress pedal until I let off and it comes back on it or a short cutoff if I stay right around the bottom of throttle and feather.

 

Not sure if your dfi is batch or sequential l. Batch could shut down the injector driver if a coil is shorting. Sounds like your not running a multec style injector so it might not be that.
Wonder if you have a fuel pressure issue.

 

Not sure what "Batch" or "Sequel" mean.

Just installed a new Bosch 044 just because.

Car is running fine........In the trailer. Wont find out until Xmas trip..

Thanks,
Kevin

 

UPDATE:
Just got back from Glamis, what a terrible trip. Car starting cutting out on first trip, barely made it back. By morning would not even run without starting fluid being sprayed. Every once and a great while, car started and runs great for about 30 seconds, then it just shuts off, like a switch.

ECU is a Gen 7, 77040, Ver 3.1 10/02

What I do know:
I have spark and fuel is flowing out fuel rail under pressure when pump switched on. on rare occasion it ran, fuel pressure was 43, vacuum removed. Car will run on starting fluid. Did get another TPS Code. Could be byproduct of shutting off I guess.

*******It appears the injectors are not getting a pulse signal when it doesn't run.*******

Local Glamis repair shop guy said that when this system was more widely used, 90% of the time it was the distributor due to moisture. Took cap off and switched on, then cranked. Got a Red and Green light, one of them flashed when cranking(cant remember which). No idea if this indicates anything.

Parts replaced:
Fuel pump
Fuel filter
Checked all fuel lines(Not that old)
TPS (3 times) Set to .50v
Coil and Coil wire(same that was on it)
Replaced Acell 6 IGN box(Same that was on it)
Cap, rotor and wires fairly new
Re-grounded ECU and IGN box
Reprogrammed with multiple tunes (It does ask me if I want to re-calibrate or use current settings. Don't recall that before).

I've got a Distributor coming. will try that next....

Any Ideas?????? ECU>> I'm out of Ideas...

Thanks, Kevin

 

What did the datalogs show?
Youre getting a tps code most likely because it needs to be greater than .2v at idle. You may have to grind a slot in the switch in order to rotate it for a higher reading.
That’s a very old ECM, one of the first versions. But if it’s seeing an ignition signal then it should fire the injectors.
Do you have a noid light? If not grab one and connect it to the injectors when it acts up. That should tell you if it’s an internal wiring or ECM issue vs pressure or other.
Hope this helps.

 

The TPS is set to .5v. Fuel pressure remains Constant 43psi when cranking or during brief running moments. No pulse at noid light.

 

I'm guessing .5 on the low side? Does it change consistently when you move the throttle? I'd still do a log as well. Set it up for, TPS, MAP, RPM, and O2 as the base parameters.

It's probably seeing an ignition signal because the pump is running. But just to be sure, while booted up with it on the dashboard, crank it and watch the rpm count in the middle of the screen. It should read 150rpm or so during cranking.
If it does then you most likely have either an ecm or wiring issue. It won't fire the injectors until it sees an ignition signal first. From there it'll energize the drivers for the injectors. If all of them aren't firing then I'd look at the ground coming out of the harness. You may want to check the inj plug at the main harness as well to confirm current and ground there too.
Again that's a very old box, 15 years, it may have breathed it's last breath.

Thanks.

 

If you determine it’s the ecm you might be able to work a deal here.

https://www.thirdgen.org/forums/engi...accel-gen.html

 

Found a ecm on Ebay, same year and version.

Is there any setup required or can I just plug it in my car and download my file into it through CAL Map?.

 

YOU really don’t want to buy another one of those. Find something newer, they’re out there.

 

What would I get to replace it without having to change the harness, sensors, dist, etc...?

I'm looking plug and play with what I got now..

 

A Gen 7 that’s version 4.0 or higher or a Thruster version 1.0.2. Either one will be plug n play.

 

Ok, so I went out to trailer to further diagnose car and wouldn't you know it, it ran perfect.

I did take a few logs of it running, but it wont let me upload them.

Kevin

 

 

Im trying to upload it from my computer. Site says it's an invalid file.

 

Try zipping the file then attaching it.

 

Thy are only 6kb...The legend for up-loadable files does not list .log as one it accepts it apears

 

This OK?

 

 

My current tune

 

I put them in a zip folder. Will that work?

 

Running Log



Fuel Log

 

Sorry that I' screwing this up guys....

 

Your screen shots don't really tell me anything, other than the fact that your fuel map has some major issues.

 

Dare I ask. Been on this tune for 15 years as far as I know. What’s up?

 

I’ve done a few tunes on super rams and none of them look liked this. You have a Wideband correct?

 

No wideband. Just a guy with this system in his off-road car the is having issues. Any help is appreciated.

 

If you could hook me up with a place here in Orange County/inland impire, ca to take it, I would in a heartbeat.

 

Gotcha, then take it to Dave at Autotrends. Tell him Mark in Fl sent you.
Check the wiring as described first and fix the existing problem. Then you can buy a Wideband and tune it the right way or have him do it.

 

Will do, where is Dave located?

 

I can’t find any autotrends in southern calif area with a Dave?

 

Sorry he’s in Diamond Springs now.
Check the wiring etc. Then when you’re ready to fix the tune we’ll talk.

 

I ve changed almost everything, as noted above.
Should I just replace the ECM and distributor or one at a time, or is there another avenue I should do?

 

Did you check the dashboard while cranking and a noid light when it quits?

 

 

Then I’d get a Wideband and start tuning. I’ll help.