wwcagedevo8

iTrader: (10)

I have developed a weird hard to track down ignition issue with my car.


Sometimes my car starts up fine and idles great. When I do a wot pull it pulls good and no issues. Then randomly after a pull it will start breaking up on just accelerating from a stop. It will buck hard and won't even rev up sitting still. When I try revving to the stationary limiter it will only go up a little bit and cut in and out.

I know that it's not the coils because the car does this randomly. It's not the tune, or the ecu.

What all is involved with the ignition besides the ecu, cam angle sensor, crank angle sensor, and the ignition coils?

Is there a power transistor or anything?

Any help would be greatly appreciated.

Dmav1989

iTrader: (1)

mine is doing something similar to this and i replaced my map sensor cause i thought it was bad and it seems to drive better now but i noticed while logging it on evoscan that my crank signal goes to 0 after i do a wot pull and goes back to reading again and then back to 0 so it might be a crank sensor..on my car.

wwcagedevo8

iTrader: (10)

When it goes to 0 is it in decal where your not on the gas pedal at all?

Because if so then that could be why it goes to 0. I think that's normal. I haven't logged mine though.

Also, I can't for whatever reason pull up dtc's using evoscan. It gives me a j234 error or whatever.

Also, I would think with the crank sensor your car wouldn't run at all or stall out if it was doing that.

My issue is when I try to rev it will cut in and out and not rev up fully. But them sometimes like now the car is acting normal.

wwcagedevo8

iTrader: (10)

I did some wire testing this afternoon. Here are the results.

Pins 10 and 23 both have .223 output at idle from ecu. These are the signal wires for the ignition coils.

Under the hood at the connectors they both output the same. .223ish at idle. Also, currently the car doesn't have the issue so I expected this to be the results.

Both 12v sources on the ignition connectors are at 12.89 and when revved up the drop down to 12.8 or so. Is it normal for those sources to drop down like that? Also, where are these two pos wires getting there source from?

The battery volts at idle are 14.25 and when revved they stay at 14.25.

So I know my alt is good, spark plugs are fine, gapped at .020, and the coils are working when they have the right inputs to them.

So now I guess I need to sit back and wait for the car to start bucking/ breaking up to try to track the issue down again.

wwcagedevo8

iTrader: (10)

What's the CAS really doing for the car? You can unplug it and the car still runs and doesn't even bog down or anything.

The cas pos wire was 14.18 volts. I did replace the cas and thought it fixed the issue until yesterday.

wwcagedevo8

iTrader: (10)

I am going to log my crank sensor today to see if I see anything unusal. I am 99% sure that it could be the cause. Everything else is checking out and its the only thing left on the table.

wwcagedevo8

iTrader: (10)

I wanted to update this thread for others with a issue like this. I just replaced the crankshaft position sensor yesterday and I havent had the issue. Upon looking at my DTC's I noticed I had 3 codes.

Knock sensor
Crank sensor
02 sensor

I know I have a crank sensor code because i disconnected it while the car was still running while diagnosing it. 02 sensor I think may come on when bat voltage is low or stalls after a startup? But the knock sensor was weird. Why would it throw the knock sensor? It only has 5k miles on it and I wouldn't think that its bad.

So if the issue comes back and I check the dtc's and see knock sensor it makes perfect since. When the knock sensor goes fault the car goes to limp mode and runs low oct map I think and that would explain why it spits and sputters at all rpms and won't let me rev up.

We will see here around 5AUG I will be making a 400 mile trip in the car so if its going to do it again I would think it would be then.

wwcagedevo8

iTrader: (10)

Update, after tuning my car on 91oct just for a extra map for crap gas I went to do a 1-4 pull to insure everything was good. The car started to break up again at wot when I punched it in first. It basically feels like the car blows the spark out or turns the fuel pump on and off. When I let off the car idles but seems like it kinda has a miss because a/f's are 12.7's instead of 13.8's that it normally is. If anyone can help with this please let me know what could be causing this. Later as I was driving home the car started working right again and I did a 3-4 pull.

So sick of this random issue! It's testing my knowledge and driving me nuts!

wwcagedevo8

iTrader: (10)

Has anyone had this issue and it being the fuel pump? I am starting to think that could be the cause. Its a modded 255 intank pump pushing through a bosch 044 inline pump on a hobbs switch. I know the 044 is good, but I am starting to think it could be the 255 intank.


But that doesn't explain the at idle breaking up sound that I hear. I have gsc s3 cams but this is a ignition breaking up sound at idle. Maybe the cam angle sensor I replaced went bad for some reason.

wwcagedevo8

iTrader: (10)

I have been thinking. Maybe I need to turn up the psi activation on my hobbs switch for my secondary pump. I am going to turn it up to 7 psi and see if the issue persist. For some reason I am thinking it will and something else is causing the issue.

wwcagedevo8

iTrader: (10)

Update, I just took the car out to see if I could get it to break up again. Like clock work it started to do it again. After a couple pulls it was back to breaking up. This time however, when i would floor it the car would act one like the fuel pump turn off, then let off it would come back and still cruise with light throttle. When i would barely hit the gas the car would rev out and not cut out at all....


Anyone else agree that this is my intank 255 pump?

Has anyone else with a pump issue noticed this same issue? Please chime in.

wwcagedevo8

iTrader: (10)

Update for others having this issue. It ended up being my primary fuel pump. Installed a new walbro 255 intank and now the problem is fixed. This was so tricky to track down but it's fixed now. I hope this can help anyone else having this issue.