WOT stutter...racegate, inj's, ???

[Quickturbosix]

OK car seems to run real strong untill the boost peaks at its set level or atleast in its last 3-4 pounds. The car then seems to stutter almost in tune with the racegate opening and closing.

19psi and is rock steady
o2's @ 800 ish
no KR
inj pulse 93% is the hghest I've seen in the 80's most of the time
maf is maxed
static fp set at 45 as per the chip
fp goes up pound for pound
tapped on the MAF and seems to be fine
took the TPS TEC out no diffrence
coolant never higher then 168*
MAT was in the 70-80* range I think

The boost is rock steady and the car still pulls but not as hard as it should. You can feel the car buck just a little. I know I'am not using all the turbo at only 19 psi. But I'am using a extender chip for 98 octane and only have 92 in the tank. So I turned the boost down just to get a good base line on how the car is going to run and handle. To make up for the 92 I have added a little fuel at wot and taken out some spark, 4% rich and the middle setting for the spark I think its -2.5* after 4400 or something close. I dont have the sheet in front of me to remember. Any ideas on where to start looking for this stutter or buck? My buddy thinks the racegate dosen't open and close fast enough yet the boost remains rock steady. Could it be a injector not working right? Seems to only make a very little change on the o2's from 4%-12% on the T+. The ar never gets out fo the 12.x:1 range.

I also get a lot of "knock" sometimes but no "knock retard". Is it possible to get a lot false knock but no retard? The way I understand it is the "knock" isn't always a problem untill you get the "knock retard" to go with it. Is this true?

Thanks guys...

 

[MARINES185]

how do you know your getting knock and its not cutting back
the timing? if you have audible knock and the computer
isn't doing anything then your doing alot of damage. either
your electronic spark control module isn't working or your
knock sensor is bad. if you have a knock gauge in your car
and it indicates knock your computer should correct. it can't
tell between false knock and real knock. if the knock
sensor sends a signal the esc module must assume its
real.

 

[Quickturbosix]

I'am using DirectScan and its shows knock from time to time but doesn't show any kr. Plus the o2's in the 800ish and a ar of 12.x:1 the car is rich. Taking out the timming its only seeing 18.5* of timing in the upper rpms. No real reason it should cause and detination.

Also the car trips no codes. If the ESC was bad it would trip a code I would think.

 

[Chyke]

Questions?

It is possible that you have a multitude of problems, and you really haven't provided that much information. I highly doubt that you are having any difficulty with your race gate, unless something is broken in it or you don't have it set up correctly. Hopefully you don't have it mounted on your cross over tube. I know a lot of people will tell you how successfully they run it there, but have those people ever mounted it in a place before the turbo where all the exhuast pulses are combined and flowing in the same direction. I had a similar problem and when I had the car on the dyno jet and used the telemitry to track boost pressure it would peak at 26psi and ocillate between 19 and 26psi. When I spoke to turbonetics they asked why wasn't it mounted below the turbo. I explained that many others had it on the crossover with luck. Well I did more research and set it up below the turbo. I modified the factory header to accomadate this. Well next dyno run was much more successful. Boost stays exactly where I set it with zero fluctuation or creep. When it was on the cross over and the boost was ocillating on the dyno, this was undetectable with the boost gauge mounted in the car, which held rock steady. This is just one idea. Than you may need to change/check your plugs, you may also have an electrical inefficiency. You failed to mention when this started. Was it after changing something, or was it out of the blue. I'm sure if you can provide some further info, someone can help. Good luck ps, email me and I'll send you some pics of my wastegate setup.

 

[Quickturbosix]

Hmm well you guessed right. I put the racegate on the x pipe. It is a BGC ss piece. The combo is all new in the car. It is a fresh combo from cam, heads, tb, turbo, injs, T+, everything. Bought everything over the course of several months and waited to put it all together when I had all the parts. I really think my combo should click.

I did change the plugs. I have tried 2 sets, 44's and 43's. The first set (44) ran the same as the second (43). The first set looked perfect when they came out. The 43's look just as good.

The charging system seems perfect. Pulls right about 14 volts with just a little throtle. Pump is hot wired with a 8 awg wire straight off the alt. The pump on the other hand is almost 2 years old and did sit for 10 months without running. But fp looks good on the guage and goes up pound for pound with the boost. I have the top $ in car electric AutoMeter setup. It was like $220 so I would think it would correctly.

I just dont understand it. The DS #'s don't look that far off to make it run like it does. I have put a ton of time in this thing in the last 4 months. I must be a little burt on it and missing something really simple.

Could 19psi be below the map for the turbo? Maybe a little more boost will actually smooth it out? I have heard this on some turbos.

 

[Quickturbosix]

Update, but still need some help here...

#1 is it possible the racegate isnt working right? I have the bolt almost all the way out. The car is making 15psi @ wot. It almost sounds like the racegate starts to "flutter" @ wot. Does it need more pressure on the bolt (or spring) to make it stable? The boost guage is showing no flutter and rock steady boost.

#2 If I dont put it all the way to the floor it runs fine. Keeping the pedal just off the carpet gives about 10-12psi. No miss or stutter. Only happens when its @ wot.

#3 I get full charge on the alt @ wot. So I dont think I have a electrcal problem.

I have tried the following....
With and without the TPS TEC.
Running rich.
Running lean.
More timing.
Less timing.
Higher boost.
And Lower boost.

Always getting the stutter or miss @ wot.
Anyone have any ideas. Dont be shy I have no problems trying just about anything.

 

[TurboBob]

Try some Octane.

Race gas mixed in will really help
stabilize the combo.

Possibly the coil module or coilpak is giving up at higher boost.

Are you sure your boost gauge is working right? I got bit by this once....

Chyke's idea about the xover wastegate acting up is an interesting one.

Bob

 

[Quickturbosix]

Yeah I got almost pure 100 in tank right now.

Its really wierd I only have to lift my foot about a 1/4" and it goes away. Going to swap some parts on Saturday and see whats up.

I will be sending you that chip via overnight ups on monday. Look for it on Tuesday.