Cali Z

Okay I've had this car for almost a year now. I've done basic maintenance on it and for the most part the engine runs well for what it is. The car is an 85 Camaro z28 with a 305 (201 block) with stock tpi on it. I am not positive what the heads and cam are. Apparently the engine was rebuilt with no performance parts just a stock rebuild shortly before I bought the car and the transmission was rebuilt too.

Just some background info-
So engine is pretty much all stock with recent tune up parts, new filters, dynomax muffler, a new cat, and a/c delete. Its an auto 700r4 with the stock 3.23 gearing I think, and it's non-posi, or broken posi one of them.

The Problem/Question

I have run the car at Sac raceway (sealevel) on 3 different occasions, each time I have gotten faster. My first time I got a 16.5 @ 82-83 mph. My second time I bested a 15.9 @ 85 mph (Timing corrected to 8 deg adv, a/c delete, tuneup). My 3rd time I got a 15.8 @ 86.3 mph w/ 2.3 60' (cooler weather no changes otherwise). Now on all of these runs I was nearing the traps @ around 3,500 rpm in 3rd gear. But everytime that I have run the car right when I am nearing the traps I look at the tach and it gets to 3,500, stops, and begins to drop in rpm. I can audibly hear the motor begin to wind down and the car stops pulling. This is the only time I have ever had this happen as I have never gone 3500 rpm in 3rd gear at full throttle on the street. I have asked a few people what this could be but most just give me a confused look and say "that's wierd". A few have said that it may be my tcc locking up. I know it locks up at 40 mph when I'm crusing but I was unaware that it would do that at 85 mph in 3rd gear at full throttle. How come I never hear of anyone else's tcc doing this? Or is it even what is happening? Could this be a fuel related issue, and if it was why would it only happen in 3rd gear? These times seem just a bit slow from what most others in an 85 camaro can run, and I'm wondering if maybe this is contributing to my times being slightly on the slow hand although they have been getting better.

Does anyone have any input about what is happening @ 85 mph in 3rd gear at wot? I am getting headers in a few weeks, and I would like to see an improvement at the track, but I would like to know why this is happening first.
Sorry for the length, but I its kinda of hard to explain.

- Robby

Trevor86TA

Torque converter. Same thing happens to my buddies 91 GTA.

89gta383

iTrader: (5)

Is the tranny stock?

Sounds like the chip commanding lock up. You will have to raise the mph in the chip to fix it.

AlkyIROC

I can't offer any suggestions for a lockup converter which it probably is but it also sounds like it's running out of fuel on the top end. If you have a new fuel filter installed, try bumping up the fuel pressure a pound or 2 and try again.

Cali Z

thank you for the replies. yes the tranny is the stock 700r4 but it was rebuilt by the previous owner. Is this affecting my et's in significant way? Because it feels like the car is really falling off as i go across the traps. The fuel filter is new, but since then I have ran out of gas once, I heard that is not good for new fuel filters when you have an old gas tank. I will try bumping up the fuel pressure a little bit.

IHI

iTrader: (1)

I'm thinking along with Stephen, not much to offer on a lock up convertor, but from a "drag racing" standpoint it sounds alot like a fuel problem, or lack there of fuel problem. What happens is you have sufficent fuel at the beginning of a run, but the further you get down track the less fuel is kept in the carb bowls if your pump cannot keep up. I persoanlly delt with this when i had my big pump go bad and had to run a Holley red pump...lost .3 due to top end fuel starvation and car was running out of breath before the 1000' mark.

Being as your car is TB it might just be a case of the pump starting to go bad, or like you mentioned running the tank dry, some of the sediment has plugged the filter restricting fuel flow.

Cali Z

IHI and Stephen, I believe you both are right about that there is a lack of fuel getting to my engine. I tried testing it out again, and I went up a steep hill to try and simulate more load on the car to see if it really did have adequate fuel for the engine. At about 35 I downshifted into 2nd, went wot and when the rpm got to 4k it would NOT rev any higher. In fact it began to go down before I let off at the top of the hill.

I have recently picked up a code for "lean condition at the 02 sensor" and a "High voltage at the MAF sensor." Could these be signs of my fuel pump going on it's way out? It does prime all the time, and it has even been getting more and more audible over these past 10 months. So it gets very loud, especially when it is getting low on gas. The gas tank was not empty when I ran at the track if it means anything.

Before I make a decision about putting a new fuel pump in, is there anything else I should check besides getting a new fuel filter again and bumping up the fuel pressure 1 or 2lbs? If the car is going to be down for a while as I get new headers and exhaust put on, this may be a good time to attempt to fix this problem right?

This is funny, and I wonder why my times are so off.
Thank you for the replies, it is very much appreciated.

- Robby

IHI

iTrader: (1)

If it were me I'd mount a fuel pressure tester on the scharder valve to see where it's at when idleing, this will often show a lower psi than factory specs and will often be the pump itself going bad, a bad fuel pump relay or oil pressure sensor "could" be to blame, but I know with our trucks it's always been fuel pump going out and not the other little things.

Wouold be very helpful if there was a way to lenghten the guage hose so you can make a road trip and see exactly what the fuel pressure is doing at different points at idle, part throttle udner load, WOT, etc...

Cali Z

okay I know it has been a while, but to answer the question of whether it was running out of fuel or having the converter lockup, it turns out it is the converter. So is this programed into stock '85 Z28 chips, or do I have a different computer in my car because both the engine and the transmission are not the original units.
Thanks.

TraviZ

iTrader: (2)

I can tell you now, this is in the factory chip.

i checked a few maf bins i have. the force tcc lockup ranged from 75-88mph.