1985 Vette TPI system problem
06-11-2014, 11:54 AM
#1
Pro
Thread Starter
1985 Vette TPI system problem
Well its been Since Feb that i've been working this car over, i'm just about to go Carb rather than continue to work thet th TPI system... but imma give it one last try and hopefully one of you guys can help me out..
i bought the car running and one day it just simply died like it was out of gas, turns out it was leaking gas from the Front crossover tube on the fuel rail, i quickly bought new injectors and replaced all the gaskets and put it back together.. well it would start then die after so i sent it to my team shop and it turns out that the timing was off, and i was having a weird code 42 problem the car would only idle without the EST and poorly at that.. so the ignition module was changed along with the distributor plugs and wires it would then idle smoothly after that but under hard throttle would back fire?? so we concluded the ECU was at fault i have since bought a new ECU reused my old proms and at first it started with EST out and ran great turned it off and plugged in the EST and it still ran great, we thought we were done till it went for a test drive and the Engine light flashed at a million miles per hour...
after that we parked it and tried pulling a code to realize that there was now no communication with the ECU and it will still start but will now run rough and will not stay on without the throttle being held down...
this isn't my daily driver so i dont need it right away but i bought this Vette to use not stare at it in the shop.. i've been reading on a carb setup for my car from forum member (Mike 1985) in a thread from 05 lol so before i give up on my TPI i wanted to get one last opinion from u guys i'm thinking its a Ground problem but at this point im leaning heavily to just going Carb and being done with everything since i would be able to maintain my dash minus the gas gauge and code light.... help me out guys BTW my 85 has a ZF6 in it that was done in December of last year
Thanks justin
i bought the car running and one day it just simply died like it was out of gas, turns out it was leaking gas from the Front crossover tube on the fuel rail, i quickly bought new injectors and replaced all the gaskets and put it back together.. well it would start then die after so i sent it to my team shop and it turns out that the timing was off, and i was having a weird code 42 problem the car would only idle without the EST and poorly at that.. so the ignition module was changed along with the distributor plugs and wires it would then idle smoothly after that but under hard throttle would back fire?? so we concluded the ECU was at fault i have since bought a new ECU reused my old proms and at first it started with EST out and ran great turned it off and plugged in the EST and it still ran great, we thought we were done till it went for a test drive and the Engine light flashed at a million miles per hour...
after that we parked it and tried pulling a code to realize that there was now no communication with the ECU and it will still start but will now run rough and will not stay on without the throttle being held down...
this isn't my daily driver so i dont need it right away but i bought this Vette to use not stare at it in the shop.. i've been reading on a carb setup for my car from forum member (Mike 1985) in a thread from 05 lol so before i give up on my TPI i wanted to get one last opinion from u guys i'm thinking its a Ground problem but at this point im leaning heavily to just going Carb and being done with everything since i would be able to maintain my dash minus the gas gauge and code light.... help me out guys BTW my 85 has a ZF6 in it that was done in December of last year
Thanks justin
06-11-2014, 12:04 PM
#2
Drifting
Sounds lean, did you buy 24 lb injectors, or 22? What number are they? Code 42 is set when the brown wire is disconnected. Disconnect battery briefly and it will go away.
06-11-2014, 12:08 PM
#3
Pro
Thread Starter
bought 24, the code has since gone but now anytime we start the car it Engine lights flash wildly and the car wont stay on unless we keep on the throttle.. ECU is getting no communication...
06-11-2014, 12:11 PM
#4
Drifting
06-11-2014, 12:24 PM
#5
Pro
Thread Starter
thats useful data there, i'll re-check wires today and see if i can get lucky today.... i wonder if replacing the ESC would help??? perhaps the ESC is pulling timing or possibly the Damper???
06-11-2014, 12:26 PM
#6
Pro
Thread Starter
thanks for your help so far!
06-11-2014, 01:29 PM
#8
Pro
Thread Starter
06-11-2014, 07:38 PM
#9
Safety Car
I dont understand why the car would run at all without communication to and from the ECU. So many inputs to govern fuel/air/spark/timing. Use the paper clip method to try and pull codes.
What I have learned is to look at something else besides going over and over what I have already done. There are so many other things that it could be. Bad head or manifold gaskets (i.e. vac leak), failing lifter, valve spring or rocker problems, on and on. My very first project would be to run a dedicated ground to the ECU. Quick, cheap and if it doesnt work your not out much. The ECU gets really squirrelly if its not well grounded
Another thought. Even if you go carb if your trouble is mechanical your car wont run any better. Just exhaust every other option before snatching off the TPI.
Good luck
What I have learned is to look at something else besides going over and over what I have already done. There are so many other things that it could be. Bad head or manifold gaskets (i.e. vac leak), failing lifter, valve spring or rocker problems, on and on. My very first project would be to run a dedicated ground to the ECU. Quick, cheap and if it doesnt work your not out much. The ECU gets really squirrelly if its not well grounded
Another thought. Even if you go carb if your trouble is mechanical your car wont run any better. Just exhaust every other option before snatching off the TPI.
Good luck
06-11-2014, 08:13 PM
#10
Melting Slicks
Do not trust the harmonic ballancer, they can slip and if you set the timing to that the engine will run retarded and have backfireing issues.
You have to check this before going any further, turn the engine till near the top dead center mark and remove no1 spark plug on the drivers side at front of engine. slowly rotate the engine clockwise a bit at a time with a socket on the bolt holding the ballancer to the crankshaft till the piston is at top dead center and the rotor button in the distributor pointing to the front of the car.
If the timing mark lines up then you are ok, iff not replace the harmonic ballancer and adjust the timing again.
Yes if the timing is set too retarded you will get an EST code.
You can also try moving the distributor, anticlockwise will advance and clockwise will retard. adjust till you hear the engine ping on acceleration then back it of a touch.
Another issue is what fuel pressure do you have?
The 85 uses 24lb injectors and has lower fuel pressure than later c4s so you should have around 33-35 psi.
The electrical connectors that plug onto the injectors can be damaged by tugging at the wires, that will result with a rough running engine and will only run smoothly at a stable speed.
If it is running rough and missing check the headers when cold, start engine run for a few seconds and shut her down. Then check the temperature at the headers any cold ones will show up and tell you what cylinder is not getting fuel or spark.
You can swap the injector wiring from the one beside it to test.
The TPI is very reliable, i have had my 85 for 16 or 17 years
Leave the carby idea alone, a bucket with a hole will ruin fuel economy and easy starts hot or cold.
You have to check this before going any further, turn the engine till near the top dead center mark and remove no1 spark plug on the drivers side at front of engine. slowly rotate the engine clockwise a bit at a time with a socket on the bolt holding the ballancer to the crankshaft till the piston is at top dead center and the rotor button in the distributor pointing to the front of the car.
If the timing mark lines up then you are ok, iff not replace the harmonic ballancer and adjust the timing again.
Yes if the timing is set too retarded you will get an EST code.
You can also try moving the distributor, anticlockwise will advance and clockwise will retard. adjust till you hear the engine ping on acceleration then back it of a touch.
Another issue is what fuel pressure do you have?
The 85 uses 24lb injectors and has lower fuel pressure than later c4s so you should have around 33-35 psi.
The electrical connectors that plug onto the injectors can be damaged by tugging at the wires, that will result with a rough running engine and will only run smoothly at a stable speed.
If it is running rough and missing check the headers when cold, start engine run for a few seconds and shut her down. Then check the temperature at the headers any cold ones will show up and tell you what cylinder is not getting fuel or spark.
You can swap the injector wiring from the one beside it to test.
The TPI is very reliable, i have had my 85 for 16 or 17 years
Leave the carby idea alone, a bucket with a hole will ruin fuel economy and easy starts hot or cold.
06-11-2014, 08:20 PM
#11
Drifting
If you suspect the harmonic balancer may have slipped you just look at it and draw a line where the crankshaft keyway is, and the timing mark should be 10 degrees counter clockwise.
Also, fuel pressure for the 85 is 2.7 bar, or 39 psi without vacuum attached.
Also, fuel pressure for the 85 is 2.7 bar, or 39 psi without vacuum attached.
06-12-2014, 03:08 AM
#12
Race Director
That seems quite strange. The SES light is connected directly to the ECM and nothing else.
I suppose there could be an intermittent connection that caused it to flash.
It sort of sounds like there is a wiring problem with the ECM connections (some are not going to where they are supposed to). That might explain the communication problem.
The dashboard uses the same communications connection as the ALDL connector to calculate gas mileage and range. Does the instantaneous gas mileage indication look reasonable?
I suppose there could be an intermittent connection that caused it to flash.
It sort of sounds like there is a wiring problem with the ECM connections (some are not going to where they are supposed to). That might explain the communication problem.
The dashboard uses the same communications connection as the ALDL connector to calculate gas mileage and range. Does the instantaneous gas mileage indication look reasonable?
06-12-2014, 11:08 AM
#13
Pro
Thread Starter
That seems quite strange. The SES light is connected directly to the ECM and nothing else.
I suppose there could be an intermittent connection that caused it to flash.
It sort of sounds like there is a wiring problem with the ECM connections (some are not going to where they are supposed to). That might explain the communication problem.
The dashboard uses the same communications connection as the ALDL connector to calculate gas mileage and range. Does the instantaneous gas mileage indication look reasonable?
I suppose there could be an intermittent connection that caused it to flash.
It sort of sounds like there is a wiring problem with the ECM connections (some are not going to where they are supposed to). That might explain the communication problem.
The dashboard uses the same communications connection as the ALDL connector to calculate gas mileage and range. Does the instantaneous gas mileage indication look reasonable?
unfortunately my dash is out and is currently being repaired by a gentleman in austin, TX
06-12-2014, 11:11 AM
#14
Pro
Thread Starter
i had read that the balancer can cause timing problems, we hooked back up my old ECM and it ran better and the light continuously stayed on so, imma send the New ECM back and have them send another perhaps that one was bad, but i'll have to look into the Harmonic balancer! thanks for the tips ill see if we can take care of this problem...
06-12-2014, 11:14 AM
#15
Pro
Thread Starter
Do not trust the harmonic ballancer, they can slip and if you set the timing to that the engine will run retarded and have backfireing issues.
You have to check this before going any further, turn the engine till near the top dead center mark and remove no1 spark plug on the drivers side at front of engine. slowly rotate the engine clockwise a bit at a time with a socket on the bolt holding the ballancer to the crankshaft till the piston is at top dead center and the rotor button in the distributor pointing to the front of the car.
If the timing mark lines up then you are ok, iff not replace the harmonic ballancer and adjust the timing again.
Yes if the timing is set too retarded you will get an EST code.
You can also try moving the distributor, anticlockwise will advance and clockwise will retard. adjust till you hear the engine ping on acceleration then back it of a touch.
Another issue is what fuel pressure do you have?
The 85 uses 24lb injectors and has lower fuel pressure than later c4s so you should have around 33-35 psi.
The electrical connectors that plug onto the injectors can be damaged by tugging at the wires, that will result with a rough running engine and will only run smoothly at a stable speed.
If it is running rough and missing check the headers when cold, start engine run for a few seconds and shut her down. Then check the temperature at the headers any cold ones will show up and tell you what cylinder is not getting fuel or spark.
You can swap the injector wiring from the one beside it to test.
The TPI is very reliable, i have had my 85 for 16 or 17 years
Leave the carby idea alone, a bucket with a hole will ruin fuel economy and easy starts hot or cold.
You have to check this before going any further, turn the engine till near the top dead center mark and remove no1 spark plug on the drivers side at front of engine. slowly rotate the engine clockwise a bit at a time with a socket on the bolt holding the ballancer to the crankshaft till the piston is at top dead center and the rotor button in the distributor pointing to the front of the car.
If the timing mark lines up then you are ok, iff not replace the harmonic ballancer and adjust the timing again.
Yes if the timing is set too retarded you will get an EST code.
You can also try moving the distributor, anticlockwise will advance and clockwise will retard. adjust till you hear the engine ping on acceleration then back it of a touch.
Another issue is what fuel pressure do you have?
The 85 uses 24lb injectors and has lower fuel pressure than later c4s so you should have around 33-35 psi.
The electrical connectors that plug onto the injectors can be damaged by tugging at the wires, that will result with a rough running engine and will only run smoothly at a stable speed.
If it is running rough and missing check the headers when cold, start engine run for a few seconds and shut her down. Then check the temperature at the headers any cold ones will show up and tell you what cylinder is not getting fuel or spark.
You can swap the injector wiring from the one beside it to test.
The TPI is very reliable, i have had my 85 for 16 or 17 years
Leave the carby idea alone, a bucket with a hole will ruin fuel economy and easy starts hot or cold.
Thank you very much for the info imma try that if i can get off early and hopefully i can get a few pictures and what not to help the process along
06-13-2014, 02:24 AM
#16
Race Director
The outer ring on the harmonic balancer can slip, which won't allow you to time the engine correctly. Mine slipped back into the timing chain cover and ground a hole it it.
Here's how to check your harmonic balancer to see if the outer ring has slipped:
Line up a straight edge with the edge of the spoke and it should align with the timing mark.
.
Here's how to check your harmonic balancer to see if the outer ring has slipped:
Line up a straight edge with the edge of the spoke and it should align with the timing mark.
.
06-13-2014, 07:52 AM
#17
Melting Slicks
The outer ring on the harmonic balancer can slip, which won't allow you to time the engine correctly. Mine slipped back into the timing chain cover and ground a hole it it.
Here's how to check your harmonic balancer to see if the outer ring has slipped:
Line up a straight edge with the edge of the spoke and it should align with the timing mark.
.
Here's how to check your harmonic balancer to see if the outer ring has slipped:
Line up a straight edge with the edge of the spoke and it should align with the timing mark.
.
I replaced the standard harmonic balancer with a race type, they cannot move back.
Sure it costs a bit more but you will never have to worry about the balancer ruining the timing case cover, they are the only balancer i use now.
See link to see what they look like.
http://www.ebay.com/itm/POWERBOND-PB2221-SS-Race-Series-7-Harmonic-Balancer-Suit-S-B-Chev-283-350-/321405665635?pt=AU_Car_Parts_Accessories&hash=item4ad5454163
Last edited by gerardvg; 06-13-2014 at 07:54 AM.
06-17-2014, 10:45 AM
#18
Pro
Thread Starter
sorry for the absence but i finally got my another rebuilt ECU, and took the other on back to Advanced.. well the Service engine light is still blinking very very fast and im not getting any codes, the car is running with the EST plugged in but will still back fire under high RPM, idles a little rough but i can drive it down the street under light throttle no problem... the original ECU worked still but would not idle with the EST plugged in, i was getting code 42 with that ECU plugged in.. i have a video but no idea how to upload
06-17-2014, 01:11 PM
#20
Le Mans Master
Did you ck the balancer? Also, it sounds like it could be the prom. I had one go bad and the SES light would blink. If i presses on the prom it would work for a while. I ended up replacing the prom and ECU.