MATEOZ28

I have a 1991 Z28 and the best I've run is a 14.7 @ 93mph!!!

Here are my mods....

450HP *crank* 383 STROKER dynoed with stock TPI setup and no Roller Rockers.
All the freebies
1.6 Crane Gold Roller Rockers
TPIS Big mouth manifold SIAMESED
SLP runners SIAMESED
PLENIUM SIAMESED
30lb injectors
Holly in tank fuel pump
SLP 1 3/4 coated headers
3 1/2" header back exhaust
4thgen 1998 WS6 rearend w/323's
Competition Engineering adj. drag shocks
Custom LCA's
Eiback drag springs with airbag
Lakewood adj. panhard rod
Energy suspension polyurithane everything
Stage 3 700R-4
SLP 24-2800 stall
17x9.5 front ZR-1's
17x11 rear ZR-1's
powder coated white
With Dunlop SP2000 tires
Phantom Fuel pressure/tranny temp guages on dual pillar.
Hotchkis tie rod sleeve
KYB front rear sway bars
ASCD SS Hood
SSM subframe connectors
Edelbrock Strut Tower Brace
Throttle body airfiol
AFPR TPIS
MSD 6A box
MSD 8.5 Super Conductor wires
MSD High Vibraton Coil
Flowmaster muffler *not sure what model*
Low temp fan switch
Low temp thermostat
Tranny cooler
Oil cooler
Goodyear Hi Miler cooler hoses
200 NOS kit *never used*
Skulte wheel spacers in front
Modified airbox
Lakewood drag struts 90/10's
V-6 springs in front
Hypertech underdrive pully's
K&N filters <---100HP @ least right there)
Accel cap rotor
Accel ignition module *I think thats what it is*
RedLine synthetic fluids, and water wetter cooling ****.
4 wheel disc
AIR CONDITIONING from a donor car
323 gears
I know I'm forgetting alot of ****.


I've been getting a code 42 so I replaced the ECM and the module in the distributer but still the code stays. The car doesnt shoot any codes while driving just when I do a code search through the aldl does it come up with 42. Please give suggestions.

[This message has been edited by MATEOZ28 (edited August 22, 2001).]

ploegi

Code 42 is the ESC ciruit, which deals with ignition timing. Doe the SEL come on while you are driving? Does the light work????

Try resetting the ECM (pull fuse, or disconnect battery) run the car around for abit, and see if the code comes back. If it does, you will need to find out why. (There are many resources for troubleshooting this, do a search in the archives, and you should find several good ways to figger this one out)

If you do not get any codes, you need to look at what your engine is doing when you are running down the road. I suspect that with the mods you list, you are in serious need of a custom prom. The stock one, or even some of the aftermarket fellers just arent going to be adequate to the task here.

Good luck

MATEOZ28

The custom proms arent making a difference.


The light works fine but doesnt come an while driving. Everytime I clear the codes by unplugging the ECM it comes up with nothing. After a few cruises Iget home, try again and it comes up with a code 42.

ploegi

That is bizarre.... Whom are you getting your prom from? Is this a true custom, or just a generic "high performance" chip?

You get a code, but no SEL? Sounds like the programming in the chip is not quite correct.....

MATEOZ28

I got the chip from a member on the board and have burned several myself. The car takes off decent but completly losses all potential. The throttle response is poor to say the least, the top end is extremly weak, and lower is noticably weaker than my STOCK 305 was.

IROC5.7TPI

I had a code 42 and replaced or inspected just about everything.

It ended up being the tan wire leading into the ECM. Its actually the one that runs under the hood that you disconnect to set the timing.

No more 42

MATEOZ28

How do I check that wire and what could make my tachometer stop working?

Chester Cheetah-mobile

Geez with all those mods that car should run faster than that!!!!!
Smaller rear tires & a 3.73 posi gear swap (4.10 would be even better)should get you into high 13's.
You may want to check the specs on the chip you have, & make sure your timing is still right, & be sure to run good gas once you have a chip upgrade. Good luck.

8Mike9

You need to plug into the ECM (autoxray, diacom, etc) and see what the heck is going on. Most likely the fuel and spark curve are no where close.

How was the engine dyno'ed? With the EFI setup? If so, what did the shop use to control it and can you get there parameters for your own chip?

MATEOZ28

I was told they made 1 383 with the exact same specs as mine except a few less of the options I got and tested it. Now they sell it as a crate. High 13's? You seriously think thats the best I got I'm thinking mid 12's with slicks and all the kinks worked out. I'll still have the nitrous for some possible 11's.

IH8FORD

No, I think he was saying "with slicks and gear change you can run high 13's on a stock engine". I would say with your mods on good tires and all the kinks worked out, mid/low 12's easy.

Grim Reaper

If you replaced the ECM and Ignition Module, then your Code 42 is being caused by a short in your wiring.

CKT 424 (tan/blk) wire for the timing as mentioned above or CKT 423 (white) EST wire are your two most likely cuplrits.

MATEOZ28

OK, I found the wire yesterday. It looked normal from the outside but the actual copper inside of the wire was ripped. It was the white wire that makes my tach work. Thanks you guy's.

Grim Reaper

Hopefully that will get you well on the way to getting your car tuned. When you encountered the Code 42, the ECM went into "Fail Safe" Mode (which is different than "Limp" Mode).

In Fail Safe Mode, the ECM will ignore certain readings and use "pre-defined" settings to ensure your "car gets home". Now, you should get ALL of the sensor readings (and their effects) on the ECM and can do some useful tuning.

FYI, I hit high 13s with my basically stock L98 now that I have optimized my eprom (for elevation under 3,000 feet). I would like to spend some time at a higher elevation to do more "tweaking" of the eprom to get maximum performance at high elevations also.

Look at your plugs and make sure they are a nice golden tan color now that you can burn an eprom. Mixture is a major part of the tuning, but also the proper spark advance too. It is amazing how only 2* of spark advance can make a world of difference in tuning. The biggest challenge on TPI cars is controlling Knock Retard.

Pay careful attention to your EFFECTIVE Total Spark Advance by deducting the Knock Retard. Often, guys will have their Total Spark Advance over 34*, but encounter 14* of Knock Retard which ends up only giving them 20* of EFFECTIVE Total Spark Advance. I found around 26-28* of EFFECTIVE Total Spark Advance (by controlling the Knock Retard) gives me the best performance with the stock GM heads. Anymore, and I encounter audible knock and my performance falls off dramatically.