LFA951

For some reason, upon acceleration, it seems my car doesn't accelerate smoothly in 3rd gear, it seems to hold back or even pause if even for a split second. I hit 7 lbs. in first, 10 in second and 12 in third, I have a MAF with a MBC and stock wastegate, what could it be?

dime1622

At what rpms does it seem to hold back?

Zeff

has the car been sitting for a while? check ignition

Tom M'Guinn

Sounds like a classic weak ignition due to plugs, cap, rotor, or/and very often, plug wires! I trust it does the same in 4th and 5th if you floor it below 3K rpms.

LFA951

The car is a weekend car, but I usually take it out Wednesdays, to narrow the gap in between, I recently got a new TPS and 3 bar FPR, it usually does it between 4-5K rpm as it is climbing, yes, it does do it in 4th and often 5th. I got a new distributor cap, rotor, plugs and wires back in September...

Tom M'Guinn

Are your chips/fuel computer tuned for the 3 bar FPR?

LFA951

They are Pro Flo chips and MAF, just threw them on, my mechanic tried out the 8 different settings on the fuel quality **** in the back of the computer, put decided to leave it on the first one which is 0-0, said it felt best on that factory setting, backfired and cut out on other settings as I recall. How do you tune them?

hally

get a new mechanic

Tom M'Guinn

You'd need to get a wideband O2 sensor or do some dyno runs to see what's going on with your air-fuel ratio. Do you know if the chips were intended for that MAF? And, do you know if the chips were designed to run with 3 bar fuel pressure? Might be better off putting it back to the stock chips and air flow meter until you can control over the a/f ratios.

LFA951

The chips came with the MAF and my mechanic said that I need to get the screw on the MAF adjusted by someone with a O2 analyzer, so they can even out the air/fuel ratio and the guy at Promotion who sold me the MAF said I can run the Bosch 3 bar with it, since it is a "rising rate" FPR as he put it. I am going to look for a shop with a wideband O2 sensor in my area, I think Foreign affairs, German Performance or JCM Performance might have them, thanks for the advice!

tman

There's a shop in Delray beach, Diablo motorsports, my cousin runs the dyno, I could set something up on a saturday or something, I'd have to check his schedule and when he's available.

LFA951

Delray Beach is like 45 minutes from me, there's a Dyno shop here by my house, but I think he only gives you the readings, don't know if he actually adjusts it, I'll call him tomorrow...

Tom M'Guinn

A typical dyno shop will let you see what your a/f ratio is when you floor it to redline, but will not have any real way to adjust the a/f curve. To adjust your a/f curve, you generally need to replace the chips or get a piggyback fuel computer. Adjusting fuel pressure and/or playing with the fuel settings on the DME can bring the whole curve up of down across the board -- which doesn't help if you have a lean or rich spot in an otherwise ok curve.

BTW, did it always stumble when you floor it in 3rd after adding those parts(which would suggest a tuning problem); or did it just start acting up (which would suggest something went bad)?

LFA951

It doesn't always do it, it does it mostly when it's real windy, like on the freeway, it felt nice the other day on a narrow stretch with a lot of trees on the sides and not much wind resistance...