Whenever I go from on the gas (no matter how lightly) to off the gas, it feels like someone threw out an anchor. Is this common to TPI's, or is it something I should be trying to fix?

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88 IROC with cobbled together (not by me)drivetrain, 86 (?) TPI unit on an '83 305,CE subframe connectors, Edelbrock strut tower brace, polygraphite bushings all around...it handles like a dream, but man is it hard to push!!

 

I'd look into it, my '87 Z28 actually stays up to speed when I let off the gas. My throttle may be sticking though, not sure...

 

That would be because of engine braking. Either OD isn't enaging or you have some tall gears in there.

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I WOULD RATHER PUSH A CAMARO THAN DRIVE AN IMPORT

1983Z28 350w/ edelbrock performer RPM power package , dynomax shorty headers, 700R-4 with shift kit, 750cfm carb, edelbrock 3" exhaust system, 16" IROC rims and ASCD SS hood.

future mods:
completely done over suspension, black paint with flames,
T-56 almost ready to go in, TPI swap coming up

Wifes new car:

95Z28, AT, leather, T-tops bone stock for now.

future mods:
header to tailpipe replacement and a cold air intake. Then I am just going to leave it alone

 

sounds like ur Torque convertor isn't unlocking

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

 

Yep, it is engine braking, but an excessive amount (IMO). Does the torque converter normally unlock when you let off the gas? Or just when you apply the brakes?

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88 IROC with cobbled together (not by me)drivetrain, 86 (?) TPI unit on an '83 305,CE subframe connectors, Edelbrock strut tower brace, polygraphite bushings all around...it handles like a dream, but man is it hard to push!!

 

mine stays locked when im at highway speeds, 50+ but i think its something with my ECM. braking is supposed to unlock it, but it doesn't on mine.

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

 

my car used to do the same thing when id get an SES light for my MAF. On the gas the car would run normal but when u let off it felt weird loike something was draging it down. changed the MAF, havent gotten an SES light since and the problem hasnt happened since either. try and see if you can pull any codes.

 

The TCC solenoid will keep the torque converter locked (if it is already locked) when you let off of the throttle until it hits it's unlock threshold. This figure is stored in the EPROM as the speed in mph when the TCC solenoid should release the TCC. There are actually two different thresholds. The threshold is usually around 16 mph in a stock EPROM for first, second, and third gears. The unlock value for fourth gear, is usually around 35 mph (stock-ish EPROM). Any speeds above those thresholds, in their respective gears, will keep the torque converter locked until it sees a brake signal input or some other event (like WOT, at certain speeds) that triggers the TCC to unlock.

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

 

Matt's correct about the eprom controlling the locking of the TCC on deceleration. On SD eproms, there is actually a switch for "locked/unlocked TCC on deceleration". I'm not sure if there is a similar switch on all eprom types for MAF cars. The TDFs for the MAF cars by TunerCat (my BIN editor) are not well defined.

 

I thought the TCC only locked in 3rd and 4th?

 

It'll also lock up in 2nd gear, but not in 1st gear. My TCC also stays locked up when coasting/decelerating unless I hit the brakes. Breathment, if your TCC isn't unlocking when you hit the brakes, then you either have a mechanical or a wiring problem. What you can do is press the brakes with your left foot just enough to feel the car slowing down a little, then press the gas down a little (while braking) to see if the engine revs climb. If the TCC is unlocked, they'll climb a few hundred rpm or so, more if you keep on pressing down the gas pedal. If you're on the brakes and gas at the same time and the revs aren't climbing, then you know you have a problem...

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Greg Westphal
'87 IROC 355TPI/A4

 

Can anyone confirm 88blkiroc's findings? My MAF sensor is a fair weather friend at best. I just can't lay my mitts on one of those Wells units, and I don't want to drop $200+ on a stocker.


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88 IROC with cobbled together (not by me)drivetrain, 86 (?) TPI unit on an '83 305,CE subframe connectors, Edelbrock strut tower brace, polygraphite bushings all around...it handles like a dream, but man is it hard to push!!

 

I'd replace the 2 MAF relays (power and burn-off) first, clear the codes from the computer, then see if the problem comes back. The relays are a lot cheaper than the MAF sensor itself.

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Greg Westphal
'87 IROC 355TPI/A4

 

Already did the relays... I had to redo the electrical connections to them, too. There can't be many sensors left I haven't done besides the CSI temp switch (which is bad) and the MAF.

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88 IROC with cobbled together (not by me)drivetrain, 86 (?) TPI unit on an '83 305,CE subframe connectors, Edelbrock strut tower brace, polygraphite bushings all around...it handles like a dream, but man is it hard to push!!

 

are you getting any codes? does this happen every time you drive the car or just sometimes? does the car idle rough at stops when the problem is occuring? another problem that i had that you may want to check out is the EGR system. I fixed that at about the same time. mine was a mess but i put a new EGR valve in an reconnected all the vacume lines which were disconnected. the car ran MUCH smoother afterwards and another bonus is that the car runs much much cooler as well. I have not gotten a SES light since i fixed the MAF and EGR. I also tried doing relays but that didnt help. See if you have somebody close to you that has a MAF 3rd gen and if you could possibly borrow their MAF to see if the problem keeps happening. good luck man.

 

If by CSI you mean CTS (coolant temperature switch) AND it's bad, then by all means change it. The CTS has a major affect on many of the functions on the ECM, including the locking of the TCC and whether or not you are in closed loop. It can cause major driveability problems.

 

CSI is "cold start injector." It has its own temp sensor next to the CTS.
I haven't monkeyed with the EGR yet, but I sounds like I should. Thanks!!

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88 IROC with cobbled together (not by me)drivetrain, 86 (?) TPI unit on an '83 305,CE subframe connectors, Edelbrock strut tower brace, polygraphite bushings all around...it handles like a dream, but man is it hard to push!!