Quote: Originally Posted by CreepingDeath94 I would start to suspect that hypertech chip too possibly. Do you have the stock one around anywhere to try and see if it helps? Check grounds...especially the one for your computer as well. ECM doesn't take control of ignition until the rpm is about 400.

getting anywhere with it yet?

nope,been working 12 hour shifts,have had no time,thinking of parting it out and recoup some of the money im out, but like i said thats a big THINKING,was gonna order new injectors,but would hate to spend more money on it,and it not be it

well got mad at it and thought id try some things, first i primed the fuel pump a couple times,then started to pull plugs, #1,3 and 2 were really wet, and they rest were just hazed, also is there any pressure on the return fuel line?as i unhooked it, and nothing came out,but still have pressure on fuel line it self

Geez. I don't have answers, but I have a lot of sympathy. TPI can be frustrating at times. My running-rough, loss of power issues turned out to be a combination of a dying fuel-pump and injectors.

That's why a flow test is part of the diagnostic. You do mean pressure at the fuel rail, correct? Disassemble the fuel rails and see if any of the parts are clogged.

I have/had the problem in the previous thread (no job, daily driver IROC dead). Might i suggest disabling the cold start injector ? I believe it actually needs to be disabled on your chip, but you can unplug it however.

I found today that the header tube corresponding with the cold start is the only one trying to fire currently, even though I have it disabled, and disconnected. That injector ohm'd really low when trying it out... safe to say mines jacked.

Have you checked your coil ?

He has a 90 TA, no cold start.

91pontiac02
Bulletin Number: 91-6-2A Reference Number: 136501 Publish Date: 3/91 Subject: LOW SPEED DRIVEABILITY AND/OR CHECK ENGINE LIGHT CODE 43 (INSTALL KNOCK SENSOR AND MEMCAL OR PROM) Models Affected: 1990-91 FIREBIRD W/5.0L This bulletin is being revised to add the 5.0L Port Fuel Injection (VIN F, LB9) V8 engine. This bulletin cancels and supersedes Pontiac Service Bulletin 91-6-2 issued 7/90. Please discard all copies of 91-6-2.
CONDITION:
Some owners of 1990 and 1991 Firebird models with the 5.0L Port Fuel Injection (VIN F, LB9) V8 engine may comment about low speed driveability or a Check Engine Light - Code 43 - Electronic Spark Control (ESC). Comments about LB9 driveability may include idle surge, unstable idle, or stall at stops.
Some owners of 1991 Firebird models with the 5.0L Throttle Body Injection (VIN E, L03) V8 engine may also comment about a Check Engine Light - Code 43 (ESC).
CAUSE:
New calibrations have been released that refine idle speed control (LB9 only) and ESC diagnostics. A new knock sensor (LB9 Only) is also available which has improved durability characteristics.
CORRECTION:
Install knock sensor (LB9 ONLY) P/N 10456126*, and install the applicable Memcal or PROM from the table.
Service Scanner Broadcast Model
P/N I/D Code Year Engine Application **16163062 3061 AXXB 1991 LB9 Automatic with
P215/60R16 or P215/65R15 **16163066 3071 AXXC 1991 LB9 Manual (M39) with
P215/60R16 or P215/65R15
**16163075 3091 AXXF 1991 LB9 Automatic with
P245/50ZR16 **16163070 3081 AXXD 1991 LB9 Manual with
P245/50ZR16 **16163138 3271 AXYC 1990-91 LB9 Manual (MK6) **16163137 3261 AXYB 1990 LB9 Manual (M39) **16163139 3281 AXYD 1990 LB9 Automatic * 16161107 1091 AXKS 1991 L03 Automatic with California Emissions * 16161112 1101 AXKT 1991 L03 Automatic with Federal Emissions * 16161117 1111 AXKU 1991 L03 Manual (M39) with California Emissions * 16161123 1121 AXKW 1991 L03 Manual (M39) with Federal Emissions * Parts are currently available from GMSPO. Parts are expected to be available on March 25, 1991. Until then, normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. SPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be cancelled as incorrectly ordered while the 400 control is in place.
Labor Operation: T0500 (VIN E) Labor Time : 0.4 Hours Labor Operation: T1710 (VIN F - Knock Sensor and PROM) Labor Time : .6 Hour

GM TSB concerning Code 43 on the 5.0l TPI as for code 53? it could be your voltage regulator in your alternator has gone bad and it is over charging, test your charging system, look into this TSB and if that all does not work I would lean towards a bad ECM, your injectors are probably fine. but i think that copde 53 is the sorce of the problem. in order for code 53 to set you would be pushing 17 volts into the entire system, AKA bad sensor readings, and overvoltage to the ECM is probably going to harm it. get the charging system fixed, then go from there.

thanks for that, i appreciate it

hard the shop scan it, and turned out to be the injectors,3 were on there way out,thanks for all the help, but decide to convert it to carb

Chevy8588, would you know where i could get my hands on a PROM like that one? Because to my knowledge there discontinued.

So eaither one like that or one that would run a 91 rs LO3 pretty well.

I have a new old stock 16161112 "axkt" pm me for pic make me a offer !!!