Hay, whats up people?
I have a problem with a stock 86tpi trans am. When I start the car & let it warm up it has a bad hesitation. Ive changed the tps sensor & set it to .38 volts. when I floor the acelerator it back fires out of the intake manifold. Ive recently tuned the car up, oh by the way I just bought this car I have no idea about the tpi system. What mods should i perform first after I get this thing running right. I would like a 12.50 daily driver
thanx, njdaewoo

 

The TPS voltage should be set at .54 volts at idle. I do not know if this is your problems but I would reset the TPS and try it.

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1988 Formula 5L/5sp 3.45 gears, SLP cold air kit, MAS gutted, TPIS air foil, TPIS AFPR, MAC headers, Mac under drive pulleys, MAC cat back, Relocated MAT.
Best ET street tires 13.85
Best 60 FT street tires 1.930
Best MPH street tires 99.29

 

Backfiring out the intake ? ouch
Are you sure you have the cylinders firing in the right order ? or checked the timing ? I'd set the TPS up to where it should be,, you can set it up to +.08v higher then the baseline (.54 like bjankuski said)which is supposed to help throttle response too


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Da Boid

- 4 out of 5 people think the 5th is an idiot

 

I agree with bjankuski, reset the TPS voltage to 0.54VDC +/- 0.07VDC.
Then since you just bought the car I would do a full tuneup, plugs, wires, distributor cap and rotor reset the timing for 6* advance. Then reset/recheck the IAC and then the TPS voltage again.
I never trust anyone I buy a car from, sorry, but I feel better knowing where I start from and that it is done right. Also a oil and tranny fluid change won't be a bad idea too.

Good Luck!

 

With the tps sensor Ive adjusted the voltage higher than .38 but , the idle starts to really rise 1000-1300 rpm in neutral. is it suppose to do this? I thought that the tps sensor is like fuel enrichment or something. I installed a new cap & rotor, wires, plugs, changed the oil & gave the car a big kiss for luck! after that the car still had the hesitation, Damn!! no error codes on the ecu. what else am I missing? Oh, by the way. What about the plan for a 12 sec daily driver after I fix this problem. the spark plug wires are not crossed up.
thanx

 

You really are going to have tuning problems if you do not adjust the TPS and other stuff the correct way.

For example, when you adjust the TPS voltage, you do it with the ignition on and engine not running.

On this board if you look around in the tech article section, you will find out the proper way to tune an EFI TPI car.

Good luck.


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'87 L98 TPI IROCZ, AFR190 heads, 3.70 gears, ZZ9 cam, 2400 Art Carr TC, SLP 1 3/4" headers, SLP cat-back, no cat, no AC, no MAF screens, Accel manifold base & SuperRam, Edelbrock double roller timing chain, MSD ext coil & distributor, trans cooler, 52mm TB with airfoil, TB coolant bypass, AFPR(58psi), K&N filters, Hotchkis lowering springs, Car-Pro custom chip, Lay Ind. ram air kit, 265/45R16 Kumho V700 tires.
ET 13.39sec @ 107.21mph
'90 Eagle Talon AWD, no rust thru 9 winters
'99 Camaro SS, red, 6-spd, T-tops, Mcleod clutch, Pro 5.0 shifter, MAF processor, Direct Flow airlid, K&N filter.
313.7Hp & 320.6ft-lbf, ET 13.55sec @ 105.1mph
next mod: 4.10 rear gears

 

After adjusting everything,, you might also want to disconnect the battery to dump what the ECM has 'learned' and made adjustments for.

 

Doc and deadbird are right!
But you need to do it a couple of times since it seems the tuning is way out.
First, as doc said, reset the TPS Voltage to +.54V +/- 0.07V.
Second as deadbird said disconnect the battery, for > 30 seconds, to reset the ECM.

Then your going to have to set the IAC, per the tech article in the tech section. And then recheck/reset the TPS Voltage again cause adjusting the IAC will change the TPS VOLTAGE!
Again you must disconnect the battery to reset the ECM to learn the new settings.
Now check the timing with a timing light and set it if needed. If the idle is too high then repeat the tech article on setting the the IAC nad TPS Voltage and then disconnect the battery again.
It sound like the idle was low and someone adjusted the the idle screw not to the procedure. This could mess things up that is why you have to do it a couple of times in this order.
BTW is it a 305 or 350 engine. A 350 you could get it in the 12's but, I think, with a 305 you would be hard pressed to get it into the 12's without NOS or a blower if your using it as a daily driver. But I could be wrong.
Good Luck!


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89 IROC 350 Auto
Custom DUAL Exhaust
Edelbrock Performer 6085 Aluminum Heads
ZZ9 Cam
TPIS Level 5 Chip
14.01 @ 97.0mph with 2.77's gears and a bad ignition control module!
And Free mods.

 

Might help to clean the carbon out of the tb.

 

As far as a 12.50 daily driver...one of the moderators of this board, who goes by Willie, has a supercharged 305 in his 12 sec daily driver. If you want to go the 350 route, there's a magazine article elsewhere on this site detailing the buildup of an IROC that ran 12.60s. Shouldn't be too hard to run the numbers you're looking for; there's plenty of knowledge on this board to help get you there.

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Jon
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1988 Trans-Am GTA w/ L98, Futura GSX tires, and a rusted-out no-name cat-back
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Mods: TB coolant bypass...more on the way!