All,

I have been trying to figure out what is going on with my car but can't come up with anything.

Problem:

Under 50%-100% throttle above 6000rpm the car seems to be losing power. Seems to be more noticeable in 3rd and 4th gear but still noticeable in all gears. Car also idles funny, sometimes at 500rpm and sometimes at 1000rpm, depends on the day. I do not know if the two issues are related.

Tried to resolve by:

New plugs and wires.
Checking for vacuum leaks
Adjusted TPS

Replacing plugs and wires and adjusting the TPS seemed to help a little but issues are still present.

Does anyone have any ideas or things to try?

NOTE: At the end of the summer of 2009 my OMP went out and I replaced it with a new one, works great now. Can not remember when these issues started but could they be related? Could the OMP dying have screwed with my ECU?

 

http://www.banzai-racing.com/FD&S5_error_codes.htm

 

Reading the error code is how I figured out my OMP was gone but I do not have an engine light displayed at all.

Could there be a code without seeing the engine light?

 

Located by the leading coil should be a green plug with a single wire to it. Ground this wire to the negative battery terminal and w/key to on your check engine light will give you codes if it detects any. It is possible the ECU was previously damaged and the best way to check that would be to switch in a replacement and see if there is any change.

 

Sounds good, I will check for any codes and then if that doesn't reveal anything I will replace the ECU with the spare I got when my OMP went out. Too bad the 7 is in storage at the moment.

 

A bad MOP/OMP can damage your ECU, but a problem with the TPS may be a better fit. The S5 TPS is involved a lot more than the S4 version, so both idle and acceleration could definitely be affected.

 

Rocket, I adjusted and checked function of the TPS at the end of the fall with little change to the high RPM issue and a little better change with the idle issue. It looked ot me that it was in spec. I adjusted to 1.00V and it moved up to 4.5V+ as I moved through its full swing. Seems to be in spec?

 

It sounds like you tested the narrow range portion of the TPS. The FSM specs are given in resistance values: approx. 1kΩ at idle, and approx. 5kΩ when fully extended, and in volts: 1.0V idle, 5.0V extended. Whether that half a volt difference matters, I don't know.

What about the full range side of the TPS? The specs are 0.8V idle and 4.3V at WOT.

 

i didnt notice but are your aux ports opening? that may have something to do with high rpm trouble

 

Rocket- I only checked the narrow range I guess, will have to check the full range side.

Canon- I am pretty sure they are as it pulls well up to about 6k, I will check that too tho.

I need this snow to go away!

 

are all grounding point nice and fresh. i regrounded my car and got rid of the hesitation around 4k, aslos without a good battery connection it may be struggling for power at 6k. after i got that stuff inline it runs way better, and if its a s5 are your ports correct? maybe they are late or maybe u have somkind of exhuast retristion not letting the air out fast enough up in the high band, either way its something small i belive imo...

 

Canon- I also thought about an exhaust restriction so I replaced my original cats with a new magnaflow downpipe and highflow cat. So I do not think it is a exhaust restriction. I will have to check my grounds to see where they are at.

What do you mean by correct ports?

 

Check to see if the ports are contributing at all. Disconnect them and drive around a see if there is any change to your problem. If it gets worse, it probably wasn't the ports.

As Ryda said, check the connections, but also check to see if your alternator is actually charging. A non-operative alternator will give the car sluggish performance.

The idle issue may be separate, but I would check your idle valve to make sure it's clean.

Worst case scenario is that you may have damaged your housings by loosing the OMP... But I'll cross my fingers against that.

 

by correct i mean that they are opening at the stock 3800 rpm instead of higher up in the range.

 

by correct i mean that they open at the stock 3800 rpm instead of higher in the rnage, i didnt have my ports opening when i got it so i bought a air pump from walmart for 10 bucks and rigged i to a msd rpm activated switch, set it for 4k at 4 cylinders and it now open up at roughly 3800-4k and nopw the climb is much nicer OOPS posted twice sorry the internet flinkered in and out

 

The 6K power issue may be different than the idle problem. There have been several threads about this and I'm not sure if there has been any resolution. I definitely experienced it on the track (car would get to 6k in 3rd or 4th and just hang there without enough power to go any faster). In all cases it was an intermittent problem that disappeared after several sessions. Plugs seemed to indicate a slightly lean condition.

Chris Ludwig even has a dyno graph showing the issue, although he did not realize what it was at the time.

One random thought I had was that the ECU may think that the tranny is in neutral and is retarding the fuel. I notice that the problem no longer seems to occur now that I have disconnected the neutral and 5th gear switch sensors. I removed them because there was a short in the harness and I was blowing gauge fuses every couple sessions. I haven't had a chance to test this yet, so it's just a SWAG right now.

Good luck,

-bill

 

These are all great things to check. Thank you for all the insight. I will let you guys know how I make out.

 

I have so many things going on lately that I personally didnt have time to look at the 7. I setup an appointment at ESP in Sterling, MA because they are the only shop with a rotary tech other than a dealer in my neck of the woods.

So come to find out one of the spark plugs was found to be arching on the block. I just replaced them in the fall so I did not suspect them to be an issue. ESP checked other things before finding this simple solution and said everything else looks pretty good.

Thanks everyone for the ideas.