Hi, I went to go start the FD this morning while it was pretty cold outside(45F) and it started right up but immediately I noticed the exhaust note was much different than normal. It was idling at around 800(normal is about 1000). Also, my Autometer A/F Ratio gauge(yeah, i know they're not very useful) well at idle the gauge is normally way green(rich) but this morning when the car was acting up the gauge was all the way in the red(lean). At this point the engine was also shaking pretty badly. I was getting pretty worried about the thought that I had trashed a seal, when all of a sudden the idle bounced up and down quick and it started idling fine. The A/F Gauge was showing green and the engine was nice and smooth. It stayed this way for about 2min then started acting up again the same exact way as before. I had to move the car while it was acting up and when I attempted to do so it had almost no power(barely was able to move it down the street). Map Sensor looks fine, I think it's a bad vacuum leak or intake leak, but I'm really at a loss with this one since it is somewhat sporadic. It's been to cold out to really look at it, so I'm just trying to get a few opinions as to what to look for so I can check it out after work tomorrow. Any help is greatly appreciated.

-Ported engine, 3mm, w/ 7k miles on it
-Non-seq stock twins (53k miles)
-Power FC
-Greddy SMIC
-850cc primaries, 1300cc secondaries
-Nipondenso fuel pump
-Apexi Intake
-Full Exhaust

 

Sounds like a major boost leak. Check all the IC couplings for a loose connection.

 

not likely at idle.

 

sounds like it is not enriching fuel mixture on cold starts. I don't know that much about it. Is'nt there some thermoswitch somewhere that tells the ecu when the water temp is warm enough to shut down enrichment. If so, maybe it is bad. If not, forget i even said anything

 

OK guys, appriciate all the suggestions!

I had a chance to tear into it todayl it's quite a bit warmmer out but acting the same was, maybe even a little worse. Took out all the intake and IC piping and well as removed the UIM. Checked all vaccuum hoses that I could see and everythign looked good. I did noticesome oil inside the IC pipes and at the bottome of the IC itself. Not like pools of oil, but still enough to notice.

I got everything back together and it was still acting up. I think my stock twin are on their way out. Noticed some smoking and a little oil leaking from the secondary(rear) turbo. Could this play a role? Car was boosting fine and pulling hard just a couple nights ago.

Checked the spark plugs, they are a little dirty since the car has been running pig rich, but my last set of plugs were a lot dirtier when I changed them out.

 

Here's an interesting one though, while the engine was running I noticed it starting to get a little worse after running for about 10min. I was tapped the gas pedal and it backfiring pretty badly.

While the engine was still running I disconnected the MAP sensor vaccuum hose and the change was not very drastic. If anything it almost seemed lke it was idleing better with the MAP sensor disconnected. What are the symptoms of one of these going bad?

 

Check your computer for any codes.... that's best place to start.

 

classic sign of a blown motor/broken seal.. do a compression test and rule that out. (if the map sensor is indeed bad it would cause that to.)

 

Sounds like a dead coil!

 

i doubt it. Both coils for one rotor would have to be bad in order to cause such a violent idle like he describes. i would just check the compression first. that will rule out engine failure.

 

You're breakin' my heart man.

I am ruling out a chipped/broken seal simply because the problem is somewhat sporadic like I mentioned. It will idle like crap and backfire for a few minutes then the idle will jump around then settle down and be perfectly fine for the next couple minutes then go bad again. Like I said earlier, the thing that I think is key here is why does my A/F Ratio guage go all the way to maximum lean position when it's idleing like crap, but when it kicks over and starts running fine the A/F guage shows way into the rich where it normal has always been. Would the stock O2 sensor play any role?

 

I think I will buy a used MAP sensor off someone in the parts section to try out.

 

Check your knock sensor as well

 

Sorry man not trying to be the heart breaker. I feel your pain... TRUST ME!!!


But.. on a brighter side if it runs fine sometimes then does it other times... Then its more then likely NOT your motor.. i was under the impression it was a constant issue. Guessi should of read your thread more clearly. My apology's. Check your CAS sensor while your at it.

 

Check your TPS Values...Adjust the sensor if needed!

 

jeez man, i am having the SAME EXACT problem!! lol

only it involves more electrical...let me know if you discovered anything.. im getting worried.

 

You know, I'm beginning to lean torwards the TPS as the culprit. I tested the MAP sensor and I think it's fine. Will test the TPS tomorrow and adjust it if need be. Thanks for the input.

 

If the O2 is reading lean that means theres excess oxygen left in the exhaust stream. The back fire indicates a rich mixture most of the time. Sounds like your problem is related to the ignition system. Plug, wire etc. A dead rotor can be rich and still have excess oxygen if it does not fire.

 

This is where I would start checking. Also, check the idle control valve,

 

Wasn't able to test the TPS; car wouldn't even start today. Jerry rigged a friends compression tester and did a test. Even compression on all rotor faces. I Didn't think anything was wrong with the engine itself anyways.

The spark plugs were soaked with gas, the car was probably flooded when I was playing with the MAP sensor yesterday. Tried to unflood car by removing all plugs, EGI/Fuel fuses, and cranking. Put it all back together and it still wont start... sigh... will pickup again tomorrow. The car may have to get towed to the shop for some TLC. Best part is I live 3-4hrs from the closest rotary shop(Dallas).

 

before you spend the money on the tow, spend $30 or $40 on new plugs. i've had a flooding problem before and thought i cleaned the plugs to where they should work fine, but still had a hard time getting the car started. try new ones first before you pay someone alot of $ to tow your car.

 

I can tow it down myself so it's not too bad. Just the 7 hour round trip to get the car worked on kinda sucks.

It's got the NGK racing plugs, but I might pick up some regular ones to try in it. The car needs to be tuned anyways because it's running way too rich. Just cleaned the plugs about a month ago and they're already fouled out almost.

 

I've seen stuck side seals and corner seals after a recent rebuild... unusual carbon build-up or incorrect clearances can result in this. With 3mm apex seals, one would have to wonder if the decision to go with 3mm was a result of a blown 2mm apex seal, or just an upgrade. If the original rotors were reused after catastrophic apex seal failure, there is often the chance that the face of the rotor may have been impacted by residual apex seal material, resulting in slightly reduced side seal or corner seal clearance.....sorry don't mean to scare you, but if everything else checks out fine, I'd start thinking about intermittent seal sticking.... The engine should be fully broken in at 7K miles, but running rich doesn't just result in annoying carbon build-up, it can result in poor lubrication due to lubricating oil dilution... Keep this in the back of your head but don't let it stress you out and by all means perform all the obvious checks first

 

Do you have the stock ECU? Did you check codes?

The problem could be a number of things, some of them non-obvious - the coolant temp sensor for instance.

-bill

 

Well guys I really appreciate all the help, but I think we're on the road to recovery here.

First I had to get the car unflooded, pulled the plugs again and they were trashed(RIP $120 worth of plugs ) I decided to just get some NGK 9's for now knowing that they will foul out quickly and not waste money on 10.5 racing plugs until the car gets tuned correctly. It's running extremly rich. Fuel pressure readings were also 50psi+ at idle!

Got the new plugs in and still no dice. Acted like it wanted to run but couldn't idle. I tested almost every sensor/component under the hood and all was within spec. Turns out it was the simplest thing... a bad plug wire. grrrrr.... the simplest things are always the last things I look at and they are usually the culprit. New set of NGK plug wires installed; Car starts and sounds good! The Power FC seemed to be going through its learning thing or something because for about 20min or so the idle was a little sporadic. It all evened out and after awhile and I took her out for a spin. She was running great but I held off on hitting any boost. I want to make sure everything is 100% before pushing it. I might be getting stationed somewhere else so I've held off on getting the car tuned fully, should be done in the coming weeks though.

Thanks again for everyones time and suggestions, it is greatly appreciated.