wikdzr1

I am currently experiencing an intermittent problem which is driving me nuts, every few days al of a sudden my ZR1 will miss very badly while driving, when I pull over and restart it will again run very strong until the next episode occurs. I have replaced fuel pumps, Prom, plugs, Map, IAC , Battery, disabled the VAT, any suggestions would be helpful. Could it be plug wires or coil pack that is my next area to explore? Any suggestions on which plug wires & coils to purchase? (The car has 70k miles with original wires, coils & injectors)

Regards,
Brett
92 ZR1
B&B
Rippee chip
4:10's

94ZR1

I would try plug wires first then go to coil, ecm etc
Ive heard of a lot of problems solved by plug wires
I wonder if PCV could do this?
You will get lots of help here
CF ROCKS

91redrocket

my '91 has 60K and just started missing very badly the other day... mechanic replaced plugs and wires... he said the coil packs were not the source of the problem... car now runs very strong... the wires were original... replaced with Bosch... man I love these cars !

Sgreg

Might want to consider running a diagnostic before you start throwing money at it. Intermitttant problems are hard to trace but this might pinpoint the problem before you replace some pricey stuff.

ShawnZR-1

Has it set any codes? I'd start by seeing if the ECM has "seen" any abnormalities.

wikdzr1

I will try to pull the codes tonight, thanks for all of the help

ZR1Mack

I agree with Red Rocket. I'm thinking 70 k on the wires is way too many miles and should be done . If an ohmmeter connected at the end of each wire reads over 30000 ohms the SM says to change them.

You need the plenum off to swap the wires and since you're already there you might as well meter the injectors. Someone on the forum saved me alot of time so consider it while you already have it off.

wikdzr1

I have pulled the codes by jumping pin A to G under the dash and it came up 1) H41 (4) H46,H54 (9) H72. I have been throwing cash at this problem for over 1yr shot gun approach. I realy appreciate the help! Also, what is the proper resistance for my injecters & do I need to unplug them to read them?

Regards,
Brett
Hershey PA

94ZR1

I would highly recommend a service manual A good investment for these cars
Electrically testing injectors doesnt mean they are good They can also leak. If your fuel pressure drops fast is a sign of another problem and is even easier to check than metering the injectors
I still go with wires though

Hooked on Vettes

CCM DTC 41 and EBTCM (ABS/ASR) DTC 72 are probably related.

DTC 72 will set and the Service ASR indicator will illuminate if the EBTCM detects three consecutive serial data link messages that are ignored due to errors in transmission.

CCM DTC 41 will likely be set along with EBTCM DTC 72 if the problem is a short to ground or B+ on the serial data circuit.

The DTC's indicate a communication problem between the CCM and the EBTCM.

Since you were able to pull codes from the EBTCM via the CCM by shorting Pin G to A the communication problem no longer exits.

ECM DTC 54 is low Fuel Pump voltage. The ECM monitors the voltage at the output of the Primary Fuel Pump Relay. The 12 volts from this relay supplies the 12 volts to operate both fuel pumps.

DTC 54 will set if the voltage is less than 2 volts for 1.5 seconds since the last ignition reference pulse was received by the ECM.

If the fault is detected during startup the Service Engine Soon light will stay on until the ignition is cycled off. However if the voltage is detected below 2 volts with the engine running, the light will only remain on while the condition exits.

This DTC 54 is used to detect a faulty Fuel Pump Relay.

I don't see a listing for a ECM DTC 46.

wikdzr1

Thanks for the responces, can I test the relays I think they are located under the batery correct, As for the code 41 where should I begin I do have a service manual

DDSLT5

I got a code 54 when my fuel pump fuse blew. Didn't pull that code till I was stranded on the side of the road at Carlisle when the coolant hit 176F and the secondary pump shut off!

Hooked on Vettes

Looks like the ECM monitors the 12 volts used by both fuel pumps and can detect if FP1 is blown which is the fuse for the primary pump.

It can't detect if the secondary fuel pump relay is working, or if FP2 fuse is blown or if either of the pumps are actually running.

Hooked on Vettes

I wouldn't worry about the DTC 41.
Clear the codes and see what comes back.

I can only tell you where the Fuel pump relays are on a 90 and 93.

Your 92 manual if it's a Helms, should show the position of the relays.

Drop the black plastic hush panel above passenger side foot well. Look up along the front edge of the dash. You'll see a group of 3 relays towards the transmission tunnel side.

According to my 90 Preliminary manual which could be wrong.

Closest to the transmission tunnel is
Fuel Relay1 - Horn Relay - Defog. Relay

For a 93

Closest to the transmission tunnel is
Defog. Relay - Horn Relay - Fuel Relay1

For test purposes swap the position of the Fuel Relay1 and Defog. Relay.

You may also want to take a good look at the relay socket and wiring. Some times the relay socket gets hot and you'll see burn marks which can cause a bad contact between the relay connector pin and relay socket.

The Fuel Relay2 is located under the driver side dash towards the driver side door.

I wouldn't worry about Fuel Relay2 because ECM DTC 54 can't detect if that relay is good or bad.

Did you verify if you really have a ECM DTC code 46?

wikdzr1

Thanks for all of the help! I replaced my coils, wires & vac lines under the plentum this weekend, I cleared the codes but did not get a chance to test it out yet. I will look into the fuel pump relays ASAP, will need to look up the locations in the Helms. Again thanks for the Help you guys are great.

Regards,
Brett

ZR1Mack

Let us know how you made out .

wikdzr1

I put 100 miles on her so far so good! It has never ran so smooth or strong this morning I gave a SS Z/28 a taste of true ZR1 acceleration it was fun!! I pulled the codes again when I got to work by shorting A to G and it listed 1. (c12) 9. (H72)

Thanks again,

Brett

wikdzr1

Today, I was driving along then all of a sudden my SYS would flash and at the same time my security would flash, (Service ASR )light up, secondaries turned off and would not reset back on, Airconditioning whent warm but did not trip into Auto mode. The car was idling at 800rpms and then when the events were taking place as soon as I would roll to a stop it would loose idle and shut off but it would start up again. After it restarted it ran fine. I have my VATS bypassed with a resistor under the dash also, during the events it would run fine but no secondaries. I pulled the codes by shorting A-G and 1(C12) 9(H72)

Brett

Hooked on Vettes

You need to clear the DTC 72 for Module 9 and see if it comes back. That may be a new code but you never cleared the old one.

Short A to G and let the display cycle.

Press Trip Reset button until 9.0 appears in the trip monitor area.

Press Trip ODO twice and 9.7 will display.

Hold ENG/MET until "---" appears in the speedometer area.

Turn ignition off. Then with A and G still shorted, turn ignition on. The DTC for Module 9 should be gone.

If DTC 72 was a new code, you do have a communications problem between the CCM and the EBTCM. (ABS/Traction Control).

The CCM is the master device and communicates with the EBTCM, ECM and Heater A/C programmer all on the same serial data lines.

You could try reseating the signal connector for the EBTCM which is located in the storage bin behind the driver seat.

I assume the ASR switch was on when you had the problem. Have you tried running with the ASR switch off?

wikdzr1

I will clear the code as you suggest, I have tried to turn the ASR off and it still acts up. Last night driving home from work it got real bad the car wes missing and running horrible pulled over restarted ran fine for a few miles then all over again. I am going to check out the grounds this weekend thanks for helping please keep the advice coming.

regards,
Brett