1 1/2 years now nothing but problems.


I've replaced the ECM, prom, wires, spark control module 3 times, distributer, and checked all connections.


The only wire I have not replaced is the brown and black wire but it looks fine.

Here is some information I got from a snap on scan tool....

TPS .66
at idle it was running lean but on acceleraton it was rich

timing 19deg
1000rpm 24deg
2000rpm 29deg
3000rom 30deg
4000rom 40deg

EGR 0 duty <<Replaced the ECR on the plenium but still reads 0 duty

Integrater 15 @ idle

o2 sensor working

MAP 15.5 idle

MAP voltage 236?? could be written down wrong, sounds to high.

3 knocks were found on 1-10 revs

Retarded the timing -20 degrees on one of my revs it didnt even register a knock on that rev.

coolant temp 176


A long time ago I wired up the MSD and coil a little differently than what is normal on a 1991 Z28

I used the bottle style coil instead of the stock one

The reason I did it was I had the MSD2 coil given to me and figured it would work.

Could that be the problem?

The car pulls back and forward like it has more but wont give it, I get backfire on decelleration, and the idle is around 700rpm in drive at a stop.

Mabye the information will help you help me
:hail: :hail: :hail:

Thanks btw

 

BTW I wired all the wires that were supposed to be going to the stock coil directly to where they were supposed to be going.

 

Anybody dare to try and solve my vexxing problem?

 

Have you tried switching back to the stock coil/ecm? When does the code 32 come on?(when the car idles, or at high speeds, etc?) Replaced the MAP sensor? How is the timing set?

 

Timing is @ 8deg with the EST disconnected

I have the stock ECM

Have not tried to switching back yet until I find out that this could be my problem. I mean, a coil is a coil right? Did GM put the 4 wires to the original coil for a reason?

Code 32 happens usually @ highway speeds not hard acceleration.

Brand new map sensor.

 

Can anybody help?

 

Did you use the white heat sink compound on the module or the dielectric grease?

 

Yes, everytime.

 

Hmm guess ya stumped us all... my best advice to you is to either PM a moderator like umm Vader about it, or to just call up GM, or heck do both.

 

Mateo,

Your MAP voltage displayed on the scanner should be in millivolts, but even then 236mV is a bit low (unless you're using a 2-BAR MAP sensor?). MAP voltage at 15.5" Hg should be more like 1.6-1.8 V.

I presume you are still using the TPI? If so, try the standard 0.54VDC for the TPS.

Another thing to remember if you are using a stock PROM, or one with stock CTS parameters - there are some critical engine control parameters that occur at spcified temperatures:

Coolant Temperature Sensor Related Parameters
BLM enabled between 50°C (122°F) and 140°C (284°F)
Cold spark advance disabled above 56°C (133°F)
Hot spark retard begins above 116°C (240°F)
Highway Mode spark advance > 59.8°C (140°F)
Knock sensor disabled below 66.5°C (152°F)
Power enrichment at base A/F ratios > 56°C (133°F)
Target IAC idle RPM >80°C (176°F)
IAC multiplier at 1.0 (base) > 32°C (90°F)
Knock Control enabled > 67°C (153°F)
EGR Duty-cycle enabled at 56°C (133°F)
EGR Duty-cycle at MAX >80°C (176°F)
TCC lockup enabled >50°C (122°F)
SHIFT light enabled >50°C (122°F)
Diagnostic communication enabled at 70°C (157°F)
DTC 43 enabled > 90°C (194°F)
Cooling fan #1 enabled at 107°C (226°F)
Cooling fan #1 off at 104.7°C (220.5°F)
Cooling fan #2 enabled at 115.2°C (239.5°F)
Cooling fan #2 off at 110°C (230°F)
Cooling fan duty cycle at 100% at 80°C (176°F)
Acceleration enrichment multiplier at 1.00 below 80° C (176°F)
Acceleration enrichment multiplier at 0.75 above 80° C (176°F)
Acceleration enrichment multiplier at 0.50 above 104°C (220°F)
Acceleration enrichment decay factor at 25% below 80° C (176°F)
Acceleration enrichment decay factor at 40% above 80° C (176°F)
Acceleration enrichment decay factor at 50% above 104° C (220°F)
Acceleration enrichment decay factor at 60% above 128° C (262°F)
Fuel limiting factor timer at 217 counts below 80° C (176°F)
Fuel limiting factor timer at 169 counts above 80° C (176°F)
Code 13 (oxygen sensor fault) enabled above 70°C (157°F)
Code 14 (CTS high fault) enabled above 130°C (266°F)
Code 32 (EGR fault) enabled above 30.5°C (87°F)
EVAP canister purge enabled above 70.3°C (158.5°F)
Hot closed-loop timer enabled above 70.3°C (158.5°F)
Rich/Lean O2 offest at 16 counts between 20°C (68°F) and 92°C (197.5°F)
A/C clutch disabled above 150°C (302°F)

Your EGR valve may also be a negative backpressure type, which can get tricky with modifications. You may need to consider changing the EGR pilot type, but you have a couple of other things to check into first.

Beyond that, the oil-filled coil shouldn't be a problem as long as it is wired correctly. The stock coil primary windings are matched to the HEI amplifier/switch module. The MSD "Blaster" can have primary impedence too low for a stock HEI module. Until your misfire problems are solved, you may want to go back to the stock coil to reduce the number of variables you have to contend with. Once your other problems are repaired, switch back to the "Blaster" if you wish.

You should also inspect the reluctor in teh distributor, and check the distributor upper bearing for wear. Any radial play in the distributor can cause variation in the reluctor/pickup coil gap and result in improper spark signal to the HEI module.

Like you needed a few more things to do...

 

Have you had the car on a dyno to see whats going on with the spark and fuel?

Your problem sounds very similar to mine, except IM getting no trouble codes. I had my car on the dyno and from 2300 to about 3400 the spark signal would just stop. The fuel curve looks great, but the signal to the dyno just stops. It got real bad today on my drive home the car just fell on its face while driving at a steady speed, and regained power. The car back fired thru the exhaust a few times while this was happening. Not just a simple miss it felt like the ignition shut off.

Do you have a pretty stout cam? My car idles around 230/240mv. I did get a code 43 the other day funny thing is the knock sensor is disabled in the chip and IM running a resistor instead of the sensor also. How could I have a code 43?

Ive replaced everything but the ECM and the reluctor in the distributor. I guess its time to give them a shot, I dunno.

 

Well I think just found out what the problem was... The ground to my MSD broke at the connector. The wire stayed in place but no contact to ground, IM surprised it still ran.....


Good luck!

 

QUOTE VADER:
"I presume you are still using the TPI? If so, try the standard 0.54VDC for the TPS."



How do I do that?

 

Check out the tech. articles from the home page. It explains it pretty good. That what I used to set mine.