A little background, I recently completed a build on my 2004 Z. It was previously stock motor with Turbonetics kit and Technosquare ECM flash. This was added to the car back in 2006. It is now a built bottom end running a ProEFI Pro48 ems and a PowerLab turbo kit. The car sat for ~2 years while I gathered parts and completed the build. Shortly after I first got the car running it had an issue where the car would go into limp mode and wouldn't allow the throttle to work at slow speeds, such as leaving my driveway or going over speed bumps. If I restarted the car, sometimes I'd have to try a couple of times, I could get throttle control back. It was annoying but I was so excited to be able to drive my car, so I didn't mind too much.

I had the car tuned. It put down 563whp on 18psi, while spinning the tires on the dyno. I had some 6 year old crappy Falken tires on at the time. I have since put on Nitto NT05 tires. A few weekends after it was tuned, the throttle/limp mode issue changed. Previously I could make WOT pull just fine. Now, if I accelerate aggressively, the car cuts the throttle control and I have to shut off and restart the car to get throttle back. But if I don't accelerate hard the car drives fine.

I pulled the codes and it showed P1122, P0222, P0122, P2135 and P0605. As well as few others, mostly related to the ProEFI and Technosquare flash on the ECM. So, I replaced the throttle body and throttle pedal assembly with new parts. I reset the ECM and did the throttle relearns. Neither part fixed my issue. A friend of mine, who is a Mercedes tech and he also helped me assemble the car back together, printed of the wiring schematics from all-data and he went over the wiring. He said everything checked out fine. Including all the extra wiring that was added with the ProEFI. I even pulled off and cleaned all the grounds in the engine bay.

So, I have done some searching on the P0605 code. There isn't too much info that is specific to our cars. However, it appears that I'll likely need to replace the ECM. Has anyone had a similar issue where you needed to replace the ECM?

If I replace with a used ECM, I believe, I can use a '03-'06 ECM as long as it is from an manual transmission car. But I'll need to have it programmed so that my key will start the car. Or I could have the NATS disabled by an Osiris tuner. Is this correct?

Any other advise on what I should check, before replacing the ECM? I appreciate any and all input. Thanks!

 

Waiting for responses. I'm curious about this even though I don't have a Z with FI.

 

nats doesnt matter, as proefi controls fuel and timing.

have you logged your TPS and APP signal while the cut happens? Are you sure you dont have any loose pins?

have you tried letting the proefi control the TB? same issue?

 

I have logged the TPS. As soon as the cut happens the TPS signal drops to 4.0. It doesn't matter if I press the throttle pedal, it doesn't move. After I restart the car, the TPS signal comes back, and I can rev the car. I'm not sure where to find the APP to log it. When I am logging I typically just click on fuel tuning and log that when I drive.

I just took the car out. With the ProEFI controlling the throttle I can accelerate and make a pull with out the throttle cutting out. However, After I made a quick pull and came to a stop, the throttle "hung-up" and the car was revving at 4k rpms. I shut it off and tried doing the throttle closed position reset and that didn't do anything. The car kept revving. So, I switched it back to the car controlling the throttle and the car idled normally. I drove it back home, hit the throttle fairly quickly and it cut out again.

Does this point to the ECM going bad?

Also, you mentioned nats doesn't matter, so I could swap another ECM in and I shouldn't have any issues? No need to program the ECM for my key?

Thanks, I really appreciate your input!

 

You might not even have to have the key reprogrammed with the ProEFI installed

 

Your car seems to be going into limp mode.

Have you checked for vacuum and boost leaks?

 

That would be real nice.

Yes, I have smoke tested it a few times. No vacuum or boost leaks.

 

On my cousins car we did the smoke test and nothing showed up but the minute we pressurized the system to 10psi with a Boost Leak Test, leaks started to show up all over the place.

 

Did you check the harness? Any water in there (has it been raining)? I don't remember all the codes off the top of my head - can you list out what each of them represent for your model year from the FSM?

 

4 out of the 5 codes are related to the TB (not the accelerator pedal). Try swapping that along with verifying all the TB wiring back to the ECM. I'd do that before swapping the ECM.

<edit> nevermind looks like you already replaced it

Since the proefi is having issues controlling the TB as well (you said it got 'stuck') I'd venture to guess you have a wiring gremlin. Maybe a pinched cable that test OK while parked but gets irritated under acceleration.

 

My thought is that since the throttle "worked" with the ProEFI controlling that throttle, that the ECM is probably bad. The issue with the throttle hanging up, I think, is that the throttle didn't learn the closed position. I had the same thing happen when the factory ECM was controlling the throttle and I replaced the throttle body. I couldn't get the relearns done via the accelerator pedal. My body has a Autel computer setup, he used it do the throttle relearns after I replaced my throttle body. I didn't use it after I replaced my pedal.

I'm torn, do i replace my ECM or change out the wiring harness? I fairly certain that the wiring is good. At least when my buddy checked it out it passe the tests all-data said to do.

 

ECMs are pretty stout. I think you may have two bad throttle bodies. It's more likely I think than a bad ECM. Wiring is possible to have burned through, so I would definitely run a multimeter and check continuity between each of the throttle pin outs and the corresponding ECM pin outs as the next step.

 

FWIW I've gotten the P0605 after an uprev flash before. Cleared it out and it didn't come back. If it keeps coming back, you may need a reflash but it's really unlikely the ECM is bricked.

 

Update: When I was looking at the car this past weekend my factory radiator finally gave up. I'm surprised it last as long as it did. The car was originally boosted back in 2006.

I found a local guy who was parting out his Z. I was able to pick up his ECM for pretty cheap. I swapped it into mine and did the resets with the throttle pedal, which is a pain to get the timing right.

Anyways, I made a quick pull and the throttle did not cut out. However, after I made another pull the throttle cut out and put the car into limp mode. I pulled the codes and these are what I got.
P0444 Evaporative Emission Control System Purge Control Valve Circuit Open
P1111 Intake Valve Timing Control Solenoid Valve
P1136 Intake Valve Timing Control Solenoid Valve
P1610 NATS Malfunction
P1611 NATS Malfunction

The NATS and EVAP code are obvious why they are showing. And when I had the original ECM in the car I had several other codes. Mostly related to fueling because of the flashed ECM and with the ProEFI. I do not have any throttle body codes anymore.

With regards to P1111 and P1136, I honestly may have over looked those codes earlier. I was focused on the throttle issue that I over looked those. My thought is that those codes are causing the car to go into limp mode. Has anyone dealt with these codes? I saw a few posts referencing superchargers cutting the wires to the solenoid and burning out the ECM. I looked at the wiring and it looks ok. However, this weekend I'll spend some time testing the wires. Does anyone have any insight? Should I replace the solenoid? Have I likely fried the ECM again? Thanks for all you input!

And if I don't get this figured out...I'll just set it on fire and walk away.

 

the proefi is controlling the cams, so its gonna throw a code

 

Well, now I'm back to the drawing board. I have no idea what is causing my issue or what to do to find it.

 

what else is the issue? the 1111 and 1136 are expected codes. Shut them off with Uprev.

 

The issue I'm having is whenever I accelerate hard, the throttle cuts out. The car drops back down to idle. I have to stop and shut off the car and restart it to get control of the throttle back. I can drive the car if I ease into the throttle, but I can't press on the throttle hard.

I assume the car is going into limp mode. I have replaced the throttle body, accelerator pedal and ECM. Nothing has helped. It is a problem that came out nowhere. The car throttle worked fine at full throttle on the dyno and for the first couple of after when I drove the car on the street.

Those codes are just the current codes that the car is showing. I was hoping those would lead me towards what is wrong.

 

The only thing I have ever experienced like that was with pins / wiring shorting out (due to water in harness for me). Looks like you have only your harness left to check. Pull the battery out of there and follow all those wires! Start with the throttle body harness...

Also I remember the intake valve timing codes being different. Those are also supposed to be soft codes and not throw a CEL.

 

I'm going to look at the harness more.

I the car drives fine with the car controlling the throttle. As long as I don't go WOT, then it cuts out and I have no control over the throttle. I have the ProEFI controlling the throttle, and I can make WOT pulls. However, the throttle kind of hangs. The car will be idling at ~2000rpms then occasionally drop down. It also has a weird issue, with ProEFI controlling the throttle, if I'm cruising at ~2800rpms and shift up a gear the rpms jump up to ~3500rpms during the shift.

This is just frustrating.