So, Ive been building my car for over a year now. New rebuild, lots of new parts, etc, etc, etc. Ive been having one hell of a time with the sequential system. I have finally got it to be able to pull a perfect boost pattern with my set up, which happens to be around 12-10-12. The only problem is that when I go full throttle it will boost up just fine, but it just really really lacks power, and has a little bit of dark smoke commin out of the pipe. Not a lot of smoke, just a little more than normal under hard acceleration.

The thing that really gets me is I found out that if I keep it at 1/4 throttle, and about 4-5 psi of boost it hauls serious ***. Well I should say it pulls like the car should at 4-5psi of boost. In other words, it pulls way harder at 1/4 throttle than full. There is a dramatic difference.

So, I thought all of this pointed to the TPS sensor being faulty. I had tried to calibrate the one in the car before and I got it very close to being within spec, but I could never get it quite in. The car has 150k on it, so I just figured it was a bad sensor. I recently bought a used sensor off the forum, and I put it in tonight hoping to fix the problem, i calibrated it all correctly.

So I go out and the exact same problem persists. Im really at my wits ends here. What else could it be? I know it cant be the o2 sensor, cause thats not a factor when the car is in open loop...

Anybody have any ideas?

 

Just thought of somethin...? Could it be the plug wires? Or maybe the ignition coils themselves....

I just replaced the plugs, I know they are perfect.

To me it just seems like its runnin way too rich on full boost.... Just some ideas.

 

I had a bad (discontinuous) plug wire which caused a misfire. The symptoms were that at light throttle applications everything was OK, but at full throttle, it felt like the boost disappeared (at that time I did not yet have a boost gauge). The bad plug wire did not feel like a miss, the engine was still perfectly smooth, but little power at full throttle.

So an ignition problem could cause what you are seeing.

 

Well let me ask this question to you. When did you first notice it? Did it just happen one day out of the blue or did you notice after you installed/tweeked something?

 

Are you seeing 12psi at WOT? Could be a cracked coupler somewhere opening at max boost only. Start w/ the y-pipe coupler.

 

It would be very unlikely to report a 12-10-12 if there was a leak.

Sam, what has been done with your injectors? Were they cleaned and tested recently? How clean/new are the plugs?

Dave

 

Theres no boost leak. I got that all sorted out a while ago.

As far as the injectors go, I have no clue on their status. For all I know, they could have 150k on them with no cleaning what so ever. The plugs are brand spankin new, so those arent a problem.

The thing is that a while ago while I was sorting out other boost related issuses, I was able to hit 12psi, but only on the secondary. It pulled sooooooo hard then, and now when I get everything boost related working properly it seems to lack the power up top.

I was also thinking maybe its the MAP sensor. I havent checked that yet. When I get back from work in gonna make sure its within spec. Haha, knowing my luck it wont be. Ive replaced almost every damn sensor in the whole engine...Air intake temp, water temp, every solenoid in the rack, turbo control solenoid, purge control, wastegate control, turbo precontrol....The list goes on and on. When will it end????

 

Damn Dave, now you have me all scared that me being a cheap *** when doing my rebuild and not cleaning and flow balancing my injectors is biting me in the ***. Geat. I kinda hope its ignition related like Dave W said. I dont have the best luck with fuel lines, haha....Ive had a fuel engine fires....

 

Well I walked that road all summer long, and changing injectors fixed it. I suggest that you consider them - I tried all manner of ignition and sensor stuff before buying a set freshly cleaned from RC. Supposedly it's possible to tell ignition from injector problems, but I never got the details on how.

My injectors only had 60k on them, and I had them cleaned by a local shop (didn't feel like waiting for shipping) with an ultrasonic cleaner. However they were not set up to flow test them since they only dealt with top-feeds. So I installed them cleaned but unverified and being a lazyass bit me. "Saving" the 2 weeks of shipping by doing them locally ended up taking dozens of hours working under the hood to sort it out.

I'm sending my original injectors out soon just to get them in sellable condition again.

Dave

 

See this is the reason why I went to microtech and single turbo.... I hope and you better too that it is not the map sensor. Very expensive brand new. The best investment you could have on your car is a good analog A/F ratio gauge. That way you know how rich or lean you are running. In the ways of sensors goes the most is the inductive pick ups, next map, O2, coolant,etc... I would look into your pettit ECU and see what it was tuned for. That might be the problem right there. Can you remember exactly when you noticed this problem?

 

So you're saying the microtech and single turbo eliminate that damn fuel injection and ignition system?

Dave

 

What i'm trying to say is that the microtech is programmable on the inj., ign., etc... That the single turbo eliminates almost all of the sol., vac.hoses, etc... The simpler the better. Sorry if this is short but Im at work and trying to answer/help. Most of the problems come from the factory. On paper they are Genius but in reality they are a nightmare. If you do the mods to help extend the life of the car (ex. all aluminum Rad. etc..) and make things more simple then less is bound to go wrong. I went through all that diag. my 7 for years. I fianlly said "screw that" and went single with microtech. Now I have more power than stock and more torqe and boost is lower on the RPM around 2,600 rpm. Which is fine by me since my twins didnt work most of the time CORRECTLY anyways. Owell back to work.

 

Thanks for clarifying. People have 'gone single' for much less rational reasons. But as it is now, having a single turbo would only help b/c the fuel rail is less crowded, and the Microtech allows you to edit the settings that the system is supposed to follow. I've not worked with a Microtech, but I'd be surprised if it can do anything to detect or fix a sticking injector or bad ignition parts.

Dave

 

Ok you are right on that. But in all honesty I have only had one 7 come in with a problem on an injector. The car had 145K miles on it. And only had #2 primary sticking. Had only 3 other cars with coils failed. I would rec. changing the wires every 50k because of heat. I use the RX8 Iridium plugs in my 7 for now since they have the same heat range. Another case where A/F gauge would come in handy. And if there where something wrong with an injector it would only take 10 mins to get to it on my car insted of 2 hours.

 

Its a pettit unlimited. Its mapped for all bolt ons. Theyre all the same.

And as far as everything else, Im going to test the map sensor, cause thats free. They go to wires...then coils...Then injectors....

Knowing my luck ill replace all of that, and it wont be working still. haha, but I guess optimism is what I need...

Oh, and for reference...The cars never worked properly. Bought it with an engine goin out, did the rebuild/upgrades. Have had every boost issue known to man. Still tryin to work out the bugs...

 

Cgotto6 - I feel your pain. I just bought a 7, that was crashed, half-*** put back together, and then sat for 4 years or so. I'm only 2 weeks into it so far. I'm having pretty good luck so far, but now my battle is to keep my boost down to 11 - 12 psi. I finally drove it to work today and watching the boost gage, it is hard to keep it down. Runs good though. I'm thinking since my car's not going to pull street duty (at least not for a long time), that on down the road a bit, I'll pull the injectors and have them serviced or replaced. The car has about a go-zillion little problems, but first I got to get it running safely.

Good luck figuring your car out. Can't remember if you said you replaced the plug wires or not, but if not, it sure couldn't hurt to do it. Like Dave W. did, and maybe you'll get lucky.

- JyRO

 

Hope you can get your problems sorted out. Ive been working on mine for more than a year now...Good luck!

I havent changed my wires yet...Thats next...

 

I Have About The Same Problem And Have Replaced Everything That Is Related To Ignition And Fuel Besides The Injectors. I Had The Injectors Flowed And Matched At The Time Of The Rebuild But Did Not Replace Them New. Ever Since The Rebuild I Have Lacked Power, Cam At Pettit Benched The Injectors For Me And Said That They Benched Out Fine. But, He Stated That Is Totally Different Than Having Them In The Car With Heatsoak And Boost. So Now Im Going To Bite The Bullet And But Some New Injectors. Its A Good Thing I Love These Cars More Than Anything Cuz I Have Spent More Troubleshooting Than My Stage 2 Motor From Pineapple....

 

wow. that sucks chasing problems. I fixed my sequential system a couple of months back. I had to replace all solenoids hoses, CCA, you name it. Pain in the ***. I just noticed DVSseven you cap every word you type. Damn man, been typing for a while? Anyway I hope you guys figure out what's up.

 

Damn dude. Your not makin me feel very good there. I better get this damn thing working right soon. I just recently broke the 3000 hours of work time spent on the car...