Hi Guys !

I am troubleshooting an issue on my race car for a while now and would appreciate some help.

I already done a lot of diagnostic on it following the Service Manual.
I'll do my best to describe what has already been done but I might forget some details ... don't hesitate to ask if not sure.

Setup details:

• 94' Integra
• B18c Block (fully rebuilt last year)
• B16a Head (Fully rebuilt - cams - valvetrain)
• P28 chipped ECU tuned on a dyno (OBD1)

Issues

1. My first problem is that my ECU cannot record ANY fault codes. To confirm this, I created issues that should throw out a code (disconnect Injector, disconnect MAP sensor ...).
   
   Every time I Simulate an issue like this, I get the MIL lamp solid while the engine is running --> Good !
   
   Then, jumping the SCS connector, the MIL won't flash any codes !?!?
   
   • After jumping the SCS connector and turning on the ignition, the cluster is doing the bulb check. All bulbs are OK and MIL is tuning ON for 1 second then turn OFF at the same time as the others. No flashing, No solid CEL.
     
   • I already confirm that I have a good ground at ECU pin D4 when the SCS is jumped.
     
   • All Fuses are good (Including ECU and Back-Up)
     
   • Tried a second ECU from another racer --> Same Results
     
   • I know that the ECU saw an issue since the CEL was on while the engine was running. But it seems impossible to retrieve these codes. It doesn't seems to enter in «Diag» mode at all.
     
   
   
   
   
2. My second and main problem is that the car will fall in Limp Mode (fuel cut at 3500 rpm) intermittently. I found out the first problem listed above while troubleshooting this one.
   
   Since I can't have the code to know the source of the limp mode, I did some test and validation of the obvious:
   
   • Tested all 4 spark plug wires (Resistance between 4k and 7kohms) --> Good
   • Tried a brand new distributor (NOT OEM)
   • Tried another ECU
   
   I know this one won't be easy without fixing issue #1 but any inputs on what could put the car in Limp mode would be appreciated.

Frank

 

What was used to tune the ecu?

 

Hi

Its been tuned on Crome.

I'll probably buy a datalogging cable from Xenocron.

Xenocron Tuning: Xeno USB Datalogging Kit #[USB-kit]

At least I'll be able to monitor all sensors directly form the ECU I guess.

I would still prefer that the original diag function (Flash codes) work.
Anyone ever seen this ?
Thanks
Frank

 

Have you tried a stock ecu?

 

No, I have 2 chipped P28.
Both can't go in diag mode.

I would be surprised if 2 different ECU (even if chipped) would have the same problem.

I might try to borrow one to rule that out though.

 

Yes, try a stock ecu.

 

Was any wiring messed with?

 

Hi Guys,

here is a quick update.

I finally found out that my tuner added a protection while tuning the car.
If ECT goes over 220, it will go into Limp Mode and trigger Fault Code 11.

This is probably what is happening ... I only have the OEM water temp gauge for now and it doesn't help.

So that should explain my Limp Mode issue. I will improve my cooling system this winter to solve it (Dual Spal fans + ducting). My ECU is perfect and been tested on my tuner test bench.

The other issue that remains .... I cannot retrieve any error codes from the ECU.
The wiring is in excellent shape now that I replaced every sensor terminals in the engine compartment.

I have the feeling that my ECU clear itself every time I turn the ignition off. I will check for constant 12 v to ECU (from backup fuse I think).

Finally, I ordered a Bluetooth adapter for the CN2 connector in the ECU. I will be able to datalog and see live each sensors value. Should help in troubleshooting.

So, let me know if you have any idea of how my ecu could auto-clear DTC.
Frank