this is my first new post so bare with me. i love my 87 gta with the tpi. its beautiful and will out run anything i come across in the first 20 miles. this car had a ton of problems when i got it. had a bad maf sensor code. it would completely quit running after so long until it cooled down to cold. i replaced it and now it doesnt leave me completely stranded. new egr valve, idles smoother and cranks at a bump of the key from cold start. ive thrown tons of parts, sensors, modules at it thinking nothing of the speedo not working and the code 24-VSS. well ive replaced everything and still no better. am i overlooking the code 24? i was told that the car could act up like this with the computer not knowing how fast its going. true or false?

btw vss sensor good. spun it up with a drill and speedo went up. i think i need to rebuild the tailshaft? plastic gears intact with all teeth. id like to have my speedo work.. if its the running problem or not. thanks for any help

 

of course it may not have anything to do with the vss. but maybe so i can get a reply with a suggestion of what the problem may be, ill elaborate on how it acts.

it doesnt start running bad at a certain temperature or after a set amount of miles but whenever it decides to act up, ill pull up to a stop sign or just slow down and when i accelerate it acts like a carb flooding itself out. the rpms wont go back up smoothly. i have to pump the gas or floor it to get back up to speed. and if i drive it much longer when it acts this way, it will put me on the side of the road. the longer i let it cool, the farther i can go before im back on the side of the road.

 

list of parts replaced- just throwin parts at it
egr valve
maf sensor- not cheap
tps sensor
iac valve
throttle body
thermostat
coolant temp switch or sensor(cant remember)
ignition coil
o2 sensor

i think ill throw a whole new distributer at it next.....$$$$help$$$$

 

my speedo has not worked in years. I would ohm out your injectors. Check your timing too. Also, your car should have a buffer box. Would be a small yellow box under the kick panel on the passengers side. If that goes out ,your speedo no longer works.

 

Don't rule out a bad ecm either. Sounds like your car is doing funny things.

 

thanks ill check that stuff out

 

your vss is absolutely critical to the proper operation of your TPI system,and just because it moves DOES NOT mean it works

 

still working on the speedo. i tested my vss with a cordless drill the other day and the speedometer went up with the speed of the drill. changed the plastic gears out with matching ones(teeth count and color). still nothing. tested the sensor again with the drill. speedometer didnt budge this time. im stumped... help. i read that tpi cars didnt have a vss buffer box so what am i 2 do?

 

finally solved the mystery. 2 things. found a burned up wire in the main wiring harness from the back of the fuse box(from gauges fuse) to the ecm. someone cut it and bypassed it to behind the instrument panel. i replaced the burned up wire and got rid of their bypass. this fixed speedometer. but my main running issue ended up being a bad fuel pump. it put out the correct pressure from cold, then when it warmed up the pressure dropped to 10psi starving the motor for fuel. changed fuel pump and runs like a champ all the time

 

new problem tho. maybe related to the shorted wire i replaced? after 2 weeks the car ran great and still runs great. BUT all of a sudden my gauge fuse started popping. it will only go a min or 2 before it pops. maybe this is why a PO put in this bypass? his bypass caused no speedometer but thats sounding better than no gauges at all. i cant drive my car not knowing my temp, oil pres, rpms, etc. any ideas on this new issue?

 

I would look at the cluster for a short to ground. Since the fuse didn't blow with the speedo out of the loop, I would start by looking around the speedo circuit. I hope you have a factory service manual with good diagrams. I couldn't imagine trying to diagnose electrical on that car without them. There was a post on my 'wiring diagrams' thread on the Electronics fourm by a member with the 87 Firebird manual. He plans to upload the diagrams to our library over at eaglemark.com, I don't know how far he's gotten. You could look him up and ask him to upload the cluster diagrams for you.

 

throw the tpi in the trash and youll be a happy camper!