a day at track

[TurboCajun]

I will do some more checking tomorrow on the harness,

[Steve Wood]

 Because you say the lights dimmed, it sounds like a short, or loose connection, in the battery cable because the lights have their own fusible link.  A big drop in the voltage will make the car miss.  The ignition comes from a different fusible link than the lights...so, again, it sounds like the problem is before the fusible bundle.

Be that it may, you should not be able to move the wiring harness under the dash and make the car miss-that is the reason I said it may be more than one problem.


Many times in the past, we have seen cars cut out when the battery cable shorted against something when the motor rolls over under acceleration.

A short causes a major voltage draw. 

[TurboCajun]

I went over all the wires, pulled, played and checked all the routing and it did nor did I see anything. I am lost. guess I may try the old module and coil. ? would the crank sensor get week under load. I looked at a log last night and the volts drop to 12. 4 but it seems that the voltage drop is after the backfire, but maybe its just reading slower than when it happens. on a test today I just went part throttle and as the boost builds you can feel the car start missing. another one of my long winded treads

[Steve Wood]

Okay....I am really confused...doe s the car miss when you move the wiring harness?  I have never seen a car that is running properly miss when you move the harness but I have seen quite a few that missed when you moved the harness and there was a wiring problem.  If it only did that once, maybe it was just a coincidence. 

You keep talking about a voltage drop like something is pulling the voltage down but now you says the voltage drops after it misses which is entirely possible if the engine cuts out for a second.  Now 12.4 v is not a sign of anything pulling the voltage down, it is a sign that the engine stopped for a millisecond and alternator was no longer charger for a short time until the engine starts again so you see the battery voltage for a split second, or the circuit that went bad-came good again.

I asked you to wiggle the ignition switch so I assumed that made no difference on the voltage being displayed by the scantool-that voltage is often wrong anyway as it is a digital conversion made inside of the ecm from the analog voltage coming in on A6.  I connected a voltmeter directly to that wire so I can compare it to what the scanmaster/pl is displaying.  I am seeing 14 volts on the meter when the PL sometimes drops to 12.9 or so.  I believe the meter.

The factory ignition module gets two power feeds from the ecm-ign fuse and the ccci fuse.  I have seen problems with the fuse socket terminals being corroded and the voltage going thru them in normal driving, bu when a load is placed on the engine, the voltage drops due to the corrosion on the terminals that will not flow enuf current to sustain the load...this causes the module to not fire the coils properly.  I always try to clean the fuse blocks terminals to make sure this is not a problem.  I have connected a meter to those two wires going to the module connector to see if voltage was dropping on them while someone else monitors the alternator output voltage.

And numerous times, I have seen the coil pak not making good contact with the mounting bracket due to paint, powder coat, loose bolts, etc.  I usually run a ground strap to the firewall to make sure the module is well grounded-cause the car will miss like a bandit if the ground path is not solid at this point,.

The crank sensor is a hall -effect sensor and my experience is that they tend to work or not work assuming the sensor is mounted with the reluctor blades on the damper passing thru the correct slot on the sensor and properly adjusted.  It is always a good idea to have someone lay under the car and watch the damper to see if the crank is moving back and forth in the block while someone revs the gas...even better if the car is in drive and foot firmly on the brake to keep from running over the guy doing the watching.  Usually, I use a timing light and watch the damper from the top for movement.  Anyway, if the damper is moving forward or backward as a little load is added to the engine, that will make it miss.

[TurboCajun]

I am not trying to confuse you Steve, I am the one that my head is spinning,
the engine does not miss when I move the wires, the only time it did was when I move the connector at the ECM and I changed the ECM and it stopped.


on one test run I seen the volts drop to 0.0 and 5.5 on the scan master and on that run i did not get a log because the power logger did not save the file. on other runs I see the volts drop to low 12s and on the one that I did get a log the volts look to drop after the backfire "on the log"


the one thing that I did not check was the ignition switch, my back told me not to even try that today, so maybe tomorrow I will get under the dash or have my son do it. I will send all day under the dash if i have to, to make sure everything is in order.


I also have an extra ground wire on the module


I also noticed earlier that my fuel pressure gauge pulses with the signal light on, it is faint but it does


I will also put my old module and pack on tomorrow.


I have to fix this its driving me crazy.


Steve thanks for your patience I know I am not the easiest person to help.

[Steve Wood]

To me, the problem is obvious.  The car is losing voltage momentarily.  What is not obvious is where the problem lies.

It all runs thru the ignition switch is why I suggested checking it.  Easy to check; use the link I gave you.  Remove the sound insulator panel under the dash-two screws under the front edge at the ends, and one stud at the accelerator pedal in the back.  Remove the two nuts that hold the steering column up just behind the dash.  Drop the column down and the switch is readily available as per the link.   Crank the car up, set the SM to voltage and wiggle the switch while watching for the voltage to change.   I sympathize with you on the back.  I have been cripple for several weeks now.

The fuses in the fuse block often do this but yours is cutting off almost completely so they are not as high on my guess list as the column.

I would not be surprised to find the TR8 causing it but you said it was happening before switching it in.  Be sure to examine the connector and make sure that none of the wires are loose in the connector and that none of the pins in the connector are pushed back so they are not making good connection when the connector is attached.

I have seen batteries that were intermittent but the problem only came into play when trying to start the car.  When the alternator is working, the problem is hidden.

If it were me, I would have probably already jumped the entire harness with jumpers coming off the harness going straight to the ecm and module bypassing the key, etc., but, I don't want to try to explain how LOL

[TurboCajun]

This morning I started early, got under the dash and pulled the switch out and cleaned the terminals, removed every fuse wiggle and replaced. voltage drop at the switch when move the wires around was 0.3 volts. after cleaning the terminals it would drop 0.2 volts. I also decided to put the old coil and module back on. I stripped the power coat from every place the a bolt went thru. and the car DID NOT  backfire, DID NOT miss, and as I looked at the logs ( i made two different ones) the first log volts stayed right at 13 volts, that was a third gear pull, the second log volts dropped to 11.7 that was a second gear pull and I think that the fans had come on.

[Steve Wood]

Get your son to clean those two fixed terminals

[TurboCajun]

well went for another ride and after a few hits and the car warmed up really good it started backfiring again .

[Steve Wood]

Fuse terminals, I meant.

Is the fuel pressure holding?

Sent from my LG-H810 using Tapatalk

[TurboCajun]

fuel pressure holds good, this damn thing runs so good at idle and normal driving, I have gone over all the grounds again,
1) could it be a bad MAF or translator
2) could it have anything to do with the Electronic spark module


I will post the logs to see if you can see something i am missing, the first one the volts stayed at 13, the second one they dropped to 11, he car did not back fire on these runs, when it did back fire again i was not logging

[Steve Wood]

if the maf reads 255 at wot throttle under boost, then it is okay.   I would prefer a real voltage instead of the one from the PL but unfortunately, I don't think there is anyway to record actual voltage on the PL.

I don't think it has anything to do with the esm but that is somewhat uncharted territory in my experience.


with regard to blow by, did you ever check the pcv?

[TurboCajun]

maf reading stay 255, i have not checked the pcv yet but I know that it does let air thru it, that is why I ordered the one from RJC . when I get a chance I will hard wire my meter to the battery with long leads to get into the car and have someone ride with me to watch the volts.

[Steve Wood]

after that, assuming the voltage stays steady, connect it to the pink/black wire going to A6 and see if it stays steady....

[TurboCajun]

did not do anything today, had to get a hair cut and cut grass on Feb,. 1