To start off my car is simplified sequential, all new hoses in the entire car, down pipe, cat back and a Pettit ECU running on wastegate pressure until the problem is fixed.

The problem started really bad, under any load quarter throttle the car would buck and not want to rev, if I lightly hit the gas I was able to go up the rpms and boost to 7psi. I changed spark plug wires and plugs and that cleared up the lower half of the rpms.

After replacing the plug wires first gear it will rev great full throttle, in a higher gear at random rpm it will begin to buck and boost will drop off. If I feather the throttle it will continue up the RPM to redline with boost. I just can't go WOT without the car bucking and not want to go. Sometimes it will start bucking at 3k rpm sometimes at 4500 but it won't want to go any higher unless I release the gas and then press it again.

Would a bad secondary turbo do this or do I need to adjust the TPS? Everything has the resistors for the simplified and it doesn't feel like it is in limp mode. All of the work was done by a very highly recommended rotary mechanic and I know his work was good. He just wanted to wait until I ran out the year old gas and got the new plug wires. I just haven't had a chance to get back to his place to have it looked at and wanted to get an opinion to maybe fix it myself and save him the time.

edit: map sensor is plugged in, hoses connected and working properly. Everything else seems to be in good working order.

another edit: Idle is rock solid, we set it a little high at 1400 but it never fluctuates stays flat at 1400.

 

First Guess: Crank Angle Sensors swapped

-Geoff

 

Could be the ignition harness, I've seen weird stuff like this with a bad ignition harness. A new one is like $80 or so and worth doing if you still have the original style harness that has the ground wire (the new one doesn't have the ground).

Make sure your plug wires are hooked up right to the correct plugs.

Finally, it could be fuel pressure or something wrong with the injectors.

It won't be anything with the turbos, that won't give you bucking and whatnot. Bad turbos just make the car slow and/or smokey.

Dale

 

Thanks guys, gonna check that all and see if that fixes it.

 

One of mine was broken so we swapped them out with used ones when we were putting everything back together.

 

Maybe your secondary injectors are wrong? you will hit a rev limiter @ 4500 if you have diff secondary injectors than your ecu thinks...this has happend on 2 fd's that I have had, first one had 1300cc on a stock ecu and car would not go over 4500ish. Would just hit like it was @ a rev limitor.

2nd once had 1680's and the ecu was for 850's and would hit a rev limiter @ 4500ish...so check that out as a possibility.

have him take off the UIM and just look and see if maybe he put the wrong secondary injectors in.

 

mine is stock injectors, I can go over 4500 I just have to let go of the gas and feather it, will boost and redline just very jerky. If I go WOT that is when it won't go past except in first gear.

 

CAS is plugged in correctly.

 

Limepro, sounded like you're in limp-home-mode. It happened to my FD before. I suggest pulling engine codes to see if you have something causing it.

If there ISNT any, I recommend disconnecting your positive and negative battery terminals, wait 10 seconds and touching them together. Then stepping on your brakes a couple times. Re-hook the car back up and see if that'll get the car out of limp-home mode.

-AzEKnightz

 

In limp mode it won't go past at all right? Mine goes past if at low throttle and past if i feather it and it is boosting. I will pull codes but everything is deleted and resistors put in.

 

We have the exact same problem and very similar mods. Your car is not in limp mode, as limp
mode cuts ignition when it detects boost (runs good in vacuum, bucks and falls on face under boost)
Dale's suggestion of ignition harness sounds promising. Seems like you have it narrowed down to ignition or fuel. As do I.

 

I will have to get video it does boost and transition. i will.be bringing it back to my mechanic just didn't have time this past weekend. I am sure he will figure it out.

 

No, limp mode WILL do the same. This personally happen to my car, and it was due to a faulty solenoid. My car would also go pass the rpm if I slowly let it go pass or if I feather with it.

Then I can drive it normally (until that 4-4500 rpm) but it will start to buck and backfire randomly, hesitation whatever you can name it it happens at around the same rpm.

I say Pull codes to see if you have anything stored in memory before trying to do anything else. Basic automotive diagnosis 101, pull codes, start from basic and isolate your problem.

-AzEKnightz

 

Will do thanks a lot for the help.

 

Pulled codes by jumping ten and gnd and nothing came up. When I put it to the ON position check engine light is on like normal then it shuts off and never comes back on, I don't think this is limp mode or I would get a code.

 

Good, now we've got that cleared away.

Now I would check on sparks to see if they are actually breaking up. However not sure if you have the proper equipement, you can try to "jump-gapping" from the ignition wires about 1" away from any chassis ground to see if you have a decent spark.

As some guy mention, this might be an issue relation to spark/ignition. Check to coils for any burnt mark on the sure, check resistance to see if they are in specs and report back.

-AzEKnightz

 

Pulled the plugs and cleaned them up, they were new and didn't look bad, reset the ecu, my TPS was a little off so readjusted to be within spec and checked the coils what is the voltage supposed to be at? I am at a little over 13 at the wiring harness, need to do a spark test. Now my idle is searching between 1400 and 1100 and I am still getting break up at WOT. It is just to damn hot to do anymore today.

 

So after some more tests and changes the car is not breaking up as bad but now it is ignition break up through the entire rpm range. I am getting full boost of 7psi up to redline as it is running off wastegate pressure. I am gonna bring it to my mechanic but I am guessing a coil is bad. I am still getting no codes so I don't think I am in limp mode. It isn't boosting as hard as it should down low but if I downshift and am high in RPM the turbo kicks right up to full boost, could this be a solenoid? all valves were replaced with the viton ones and are brand new less than 100 miles on them. Every hose in the car was also replaced at the same time, only thing reused was the solenoids.

 

Yea, sounded like you're not in limp mode. I'd recommend bringing it to your mechanic and have him diagnose your coils. Or buy a tool like this: Waekon Industries KV ARC Quick Probe - Tool Catalog - Electrical - Meters & Testers

And while having the car run/while revving with the throttle cable, place this tool right on top of each coil as it will blink and show you if that coil is firing correctly. Handy tool to have and a very quick way to diagnose the problem.

-AzeKnightz

 

I called my mechanic, he is on these boards and always parting out cars and has a sick fd, I fully trust what he tells me. Hopefully he has time for me tomorrow we shall see.

 

sounds like a plan. good luck on the repair.

-AzEKnightz

 

Gonna try new coils next weekend, rain slowed us down. Also found out I have one face on the front rotor at low compression. Rear rotor was 95 on all 3 and then the front was 90-90-60 sometimes the 3rd would bounce to 80 but it is going.

 

I have this same problem pretty much, what did you find out?

 

My new coils just came in, going to replace them tonight and test again. If that isn't it then it is a fuel problem, most likely secondaries. I will pull my old coils later and post a picture of them, I have a feeling they got damaged from humidity when they were out of the car.

 

You replacing just the trailing or all the coils?