Car falls on it's face at top end

The Darkside

Heavy Metal Thunder
Joined
May 25, 2001
Ok,I got my scan tool working again & decided to do some tuning.I punched it from about a 35 mph roll,Here's some of what I'm running & some #s that I got.
Chip: Jim Testa 93 street for 009's
Fuel Pressure:set @ 43 line off
boost: maxed out @ 23lbs.
02's started around 890,went down to around 835
Knock:0 through out run
Spark plugs:Atuolite 23's,gapped @ .035
SMC setting:15 turn on,pump speed 8,100% denatured
See sig below to see what else I've got on car.

Problem:Car was really slowing up & nosing over at the top of 3rd gear!!!Felt like it might be bogging or something.

Possible fixes:
Lower fuel pressure to lower o2's?
Raise boost 1 or 2 lbs?
Lower pump speed?
Combination of the above?
Suggestions????

The Darkside
 
Hey....I'd like to see you solve this. My car is set up almost identical to yours and it does the same thing at the track.

My mph's were only 98-99 mph running 19 lbs of boost. My 02's were reading rich just like yours.

I have the same settings on my SMC...except my turn-on point is aroung 12-13 lbs. Testa 93 chip , 009's, stock turbo, torque converter, intercooler etc.

I gave up on the alcohol and turned it off at the track. The best I ran was 13.40 using P66 105 unleaded. I basically ran out of time tuning it in on just race gas, but at least I was heading in the right direction. I haven't been back to the track since.

The only thing I can figure is that the alcy is cooling off the EGT's too much and the turbo starts to die on the big end.

The alcohol is great on the street, but I haven't got the right combination yet for the track.

I'm going to try a RA108 with some real 110 octane leaded fuel next trip.....I'm sure that will get me to the 12's. I'd sure like to get the alcy/93 octane set up to work though.
 
How's your valve springs? If they are good, then I'd try lowering the fuel pressure a bit, to lean it out.....

Mine is doing something similiar, but it's the valve springs, because it only does it after the car is fully warmed up.
 
Are you sure about the scan readings from your guage ? Some of the scan guages are 100 points + - off. Don't think 835 would make it "nose over". If 835s are correct then you might lean it out, or turn alky down. Maybe one of the alky gurus can chime in.
 
What are the timing tables in the chip? If its similiar to Joe Lubrants 93 its 18 degrees which is a great street chip with pump gas. Tune it to run 93 octane with alky to achieve no knock at 22-23# (stock turbo?). Valve springs were mention, which is a must, even with low mileage cars. Pump speed is about right but the 02's are WAY TOO HIGH. Lean out the FP. With 009's I am running 37-38 line on with 02's at 790 - 800mV @ 22#. If I run at the track I only use 110 octane with a red's 107 chip with no alky (don't need it!). Like mentioned before check the valve spring pressures and if low replace with some LT1's 100#'s. HTH


Mike Banas
 
"02's started around 890,went down to around 835"

:eek: ...Damn those o2's are crazy high...890's on my car, feels like im not even mating it. I would say, get the o2's down as long as your not detonating. Might wanna try the NGK UR5's and gap them tight .32 for high boost also, i did this and my car felt stronger on the top. And as mentioned, check your valve springs, if there are weak, the car will fall over after 85-90 mph.

Shoebox
 
The valve springs were replaced less than 15,000 miles ago,so I I kinda ruled that out.
I bouht some NGK UR5'S today and will try them out soon.
I'm not sure about the timing in testa's chip,but I believe he said it was a low timing chip.
With the line ON,I'm seeing 38lbs,with line OFF,I'm getting the 43lbs.
I just wasn't sure about how to go about leaning it out.Should I raise the boost or should I lower the fuel pressure? I mean I'm at 23 lbs boost right now with 93 gas, so I'm kinda nervous about raising the boost more ,but then again I'm not seeing any knock.

The Darkside
 
"Should I raise the boost or should I lower the fuel pressure? I mean I'm at 23 lbs boost right now with 93 gas, so I'm kinda nervous about raising the boost more ,but then again I'm not seeing any knock. "

I would take some fuel away and take it from there...

Shoebox
 
I would try lowering fuel pressure too.Go down about a pound or two.Also look into doing your tuning with an EGT guage.And that way your sure the readings are correct.I backup my o2's with egt numbers.

I too am fighting the richness...but dont mind.I do mind paying 6 bucks a gallon for race gas.

Alky tuning usually requires running 2 lbs less fuel than regular due to the enrichment denatured cuases.Its like a 7th injector kinda.
 
All good suggestions above, and some of these guys really know how to tune a car, so I don't have too much to add. True, running pure denatured will richen you up. It's nice because thier is no transitional knock. You could add water, or just go to isoprophyl alcth (93%) and try tuning with that. The cooling effect will be greater so the turn on point could be higher, and the pump speed lower.

I don't like the idea of lowering the FP, but lots of guys do it with success, so who can argue with that!

Something to try is after you hit third gear, turn the pump speed down a bit, and see if that helps. This would tell you if you are on the right track. It would be interesting to see how far you need to turn it down to get .800, or so.
 
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