New headache

rj95svt · Oct 9, 2007

I have two new problems that have just started. I drove my car to the dragstrip Sat. and I got in the car to drive to the staging lanes and it ran fine. I cranked the car to pull out on the track and it idled at 1200-1800 rpm's (it's normally around 800) but was otherwise ok so I made my pass but didn't make any more due to this problem.
On the way home I floored the throttle and got severe detonation it's never done that before so I let off immediatly and drove a little further and done it again but this time it ran fine

I done some datalogs with the tweecer and found that when I'm getting detonation the spark advance is showing 44 degrees but most of the time it's normal.

I also noticed that at idle the throttle status is showing part so I checked my tps voltage at idle it's 1.35 WOT 5.35. I set this two months ago at .93 at idle now the lowest I can get this is 1.22. Could this be my problem? I'm begining to think my tps sensor is going bad but I don't know if that could cause my detonation problem.

I also noticed the load% was showing 119 if that had anything to do with it.

I'm going to look at some of my old datalogs to see if I can find anything more.

What do you guys think?

Blackened302 · Oct 9, 2007

i can tell you from experience that a higher tps voltage will cause a raised idle. i delt w/ this a few weeks ago.

i guess that'd be a good place to start--re-adjust it and see where it goes from there.

gcomfx.com · Oct 9, 2007

If your TPS is showing higher, I would look there first. However, I feel it's worth mentioning that my car acted very similar to yours. Detonation would come and go during a full out WOT run at the track. I changed the distributor and it fixed it.

final5-0 · Oct 9, 2007

Jarad

Loads of >100% is a normal kinda thing in the j4j1 pcm
For more details, look at the scalar ... Load Scaling Switch

Sounds like something is hokey with your TPS
Perhaps you can loosen it a bit and get the value down

I'd not worry about getting it at that .98 or .99 volt thing
Just get it below 1.00 if you can

Also ... if you have your tb bleed screw out too far, the idle can hang high

As for the ping thing ...........

What all have you done to the following:

Dizzy setting
Global Spark Adder scalar
Spark Base, Altitude, Borderline, and MBT tables

When you saw the 44 spark values ...
Further define your driving conditions ... please be specific

Grady

rj95svt · Oct 9, 2007

44 degrees timing was at 1800 rpm at wot!

The only thing I've done to the timing is adjusted the top load row in the base timing table and disabled all the other timing tables by putting 55 in all the load rows. Base timing is set at 10 with no spout.

I've tried a stock cobra tune with the EGR and Smog disabled also and it still done this.

When I unplug the ISC the idle drops down to near normal at around 1,000. The timing is showing around 32 degrees at idle.

Stanger007 · Oct 9, 2007

Your idle timing at 32 is normal.

How about a vacuum leak to bump the idle higher and allow unmetered air in (lean) and screw with the MAF/LOAD?

Got a link to your datalogs so we can check it out?

It would be worthwhile checking the base timing (SPOUT out) to make sure it hasn't moved from 10deg and is not jumping around.

Wes

rj95svt · Oct 9, 2007

The car went from running perfect to acting crazy within 5 minutes. I shut the car off it was fine then I cranked it and it was idling at 1200 and above immediatly so I don't think it's a vacumm leak but I will check after I check everything else. I'm beginning to think it has to do with the PIP and the tps although it's unlikely they both went bad at the same time.

The tps thing has me puzzled because I am gonna have to slot the holes in the tps to get the voltage down below 1.22 where I had it all the way down to .93 before.

The odd thing is the detonation is somewhat rare but when it does it it's very bad and almost scary. My motor isn't in great shape but I don't want to tear it up.

I will double check the timing later this afternoon when I get home.

Stanger007 · Oct 9, 2007

1.22 is the upper limit of where the TPS can be and still read "closed throttle". Pull it off the TB and see what the voltage reads then, rotate it and make sure that the voltage increases as you turn the potentiometer. Your can can be in the "on" position but not running to do all of this.

I agree that it is odd to jump up that high all of a sudden, I'm curious to see what it turns out to be.

Might be worthwhile to pull the codes also if that is easy for you.

Wes

rj95svt · Oct 9, 2007

Yeah I plan on pulling the codes. I never got a check engine light but it's still possible to have a code.

rj95svt · Oct 10, 2007

Well the car is idling right again! I took the throttle body off and worked on the tps for a bit. I can't out how the tps voltage changed so much. There will be no plastic left on one side of the bolt holes on the tps if I slot them far enough to get the voltage below 1. I got the voltage down to 1.08 and that was the lowest I got.

I drove the car down the road but didn't drive it very far. I didn't get any detonation but I am not totally convinced that it's fixed. I will have to drive it some more to make sure.

Stanger007 · Oct 10, 2007

1.08 is well within the spec, roll with that.

Keep us posted.

Wes

gcomfx.com · Oct 10, 2007

I recently upgraded to a FMS T/B it has an adjustable ring for the TPS sensor. I had to dial it in to get it set correctly. But it is nice to be able to change it.

rj95svt · Oct 15, 2007

Well guys my idle problem went away for awhile but my tps voltage is still fluctuating and the high idle came back for about 30 minutes and went away again. I done a datalog and my tp voltage at idle had dropped to .84 at one point. I am just gonna replace my tps and see what happens.

final5-0 · Oct 15, 2007

How about the tb blade stop screw

Do you have it cranked in a good bit

Grady

rj95svt · Oct 15, 2007

I have never been able to turn it! It's siezed up

final5-0 · Oct 15, 2007

rj95svt said:
I have never been able to turn it! It's siezed up

Could be a prob

I'd soak it real good in some penetrating oil and free it up

You want it to just barely hold the plate off the tb wall to prevent it from
sticking to the wall when it snaps shut

Grady

rj95svt · Oct 15, 2007

I have had the throttle body off and I honestly don't see any reason to mess with it because the throttle blade appears to be completly shut. I will however work on it if everyone thinks this could have anything to do with my problem but if the tps voltage is fluxuating at times and the adjustment screw isn't loose I don't see it changing anything.

final5-0 · Oct 15, 2007

I was wondering since you had an issue of getting the voltage down

Maybe it was holding things too far open

Good Luck!

Grady

SVT3183 · Oct 15, 2007

do you have an ignition box? if so, try running with it disconnected. i had a similar timing issue with a MSD 6A

rj95svt · Oct 16, 2007

SVT3183 said:
do you have an ignition box? if so, try running with it disconnected. i had a similar timing issue with a MSD 6A

Nope it's all stock.

I am not having detonation problems anymore. Oddly enough all I had to do is rewrite my tune to the tweecer and the detonation stopped. Now the only problem I'm having is high idle sometimes. It'll be perfect for hours and then suddenly it will idle at 1200-1800 rpm's. Then it will go down to normal after a while (30min.-2 hours of running).

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