help with missfire
 

Well we just returned from this year's Open Track Challenge and we spent the entire week dealing with a missfire that left us down on
power and blew a motor half way through the week. The new motor still has a miss so we had to limit our running. We're out of ideas so if you have any we would be very appreciative.
The Symptoms:
Slight miss at idle
Under throttle (above 3,000 rpm) there is a heavy missfire and hesitation (when boost comes on.)
Problem began occuring at 10 psi but then started happening even at our lowest setting
of 6 psi.

Things tried:
Fuel pump replaced.
Primary and secondary injectors replaced.
New fuel filter
New plugs
New wires
Grounds checked and added
replaced both trailing and leading coils
checked wiring to coils
no intake, vacuum leaks.

Info on vehicle:
87 Turbo
Haltech E6k
hybrid turbo
profec b boost controller
walbro fuel pump
all stock wiring removed

Thanks for any help you can provide.

-Matt
www.bfimotorsports.com

EGT or wide-band info???


-Ted

The car was tuned on the dyno to run a AF ratio of 11 at WOT. I don't have any info from when the missfire is occuring as it is very severe and prevents really driving the car.
Let me add that we have been using this same haltech map and engine setup for the last 2.5 years. The problem came on pretty suddenly. The only changes that were made before it occured was the final removal of what was left of the stock wiring system, installation of a battery cutoff, rewiring of the alternator, and removal of the charcoal cannister.
We've gone over every wire on the car and ground and can't find a problem on that side of things.
-Matt
www.bfimotorsports.com

sounds like a tuning issue. idle maybe rough(and not be a problem) but "missfire" under boost sounds like detonation. this maybe what "blew" the engine. what exactly went wrong with the engine? Also is this a modified stock "hybrid" turbo? you may also be seeing some boost creep causing bad tuning and detonation. EGT or AFM readings under boost would be helpful. Also what type of fuel?

We run 91 octane with pre-mix which is what we tuned the car on. All tuning was done very consevatively and we tuned the car up to 15 psi with no leaning out and good AF ratios. The failure of the engine is low compression on the rear rotor, pretty consistant with a damaged apex seal. The missfire occured even at 6 psi and rpm's as low as 3500 rpm. No boost creep was observed and the miss is very heavy and instantanous when throttle is applied. Not really driveable at all. (Although we did limp it around 3 different race tracks at OTC before losing compression.) The turbo is a t04 compressor with a stock turbine housing with a clipped wheel. Power levels are intentionally kept down due to the small size of the turbo. Not mentioned earlier but we do run the stock 550 injectors as primaries and 1680 bosch injectors as secondaries.
We have been running this exact same setup for 2.5 years and put probably 2,500 track miles on the car with no problems, ever. The problem developed very quickly, first at only higher boost levells (approx 10-12 psi) but now even at
the lower boost setting of 6psi.
Thanks for your help with this.
-Matt
www.bfimotorsports.com

Can you give us an idea of what kinda ignition timing you're running under those conditions?
You don't need to give us the exact numbers, but a rough value of what you're running is fine.

You might want to manually check all your maps, as "glitches" in uploads can corrupt the maps and introduce bad data into the maps which can cause horrible results.


-Ted

approx 17 degrees of advance. Maps have been re-uploaded and inspected manually. No problems that we can see.
-Matt
www.bfimotorsports.com

broken apex seal sounds like detonation. what intake air temps is this setup running under boost and what plug heat range are you using? with 91 octane you are going to have problems at racing speeds, this fuel is just to inconsistant and can vary widely from different vendors. Apex seal was likely damaged when the engine started running roughly and then finally failed. I would start with race fuel and lower the timing. this would be after I checked all coils, plug wires, plugs, and all wiring to and from the Haltech. the turbo setup you are running tends to develope alot of heat at prolonged boost and this will lead to detonation. I was not able to make this setup work very well on another car. lastly what type of intercooler?

Are you reading this straight off the bars?
Or is this total advance?
Most users set base to -5 at idle, and since the E6K (and E6X?) cannot do negative ATDC timing, all the other bars need to adjust -5 for total advance.
If this is the case, your 17BTDC is actually 12BTDC?


-Ted

As I don't pretend to be a engine management guru I provide these datalogs for your viewing pleasure. Maybe you can pull more useful information from these than I can.
A datalog taken during the missfire. The missfire was heavy and acted as though I had encountered an ignition or fuel cut. Very violent.
http://www.bfimotorsports.com/matt/haltech/APR4_2.HDL

This datalog is taken with the same engine settings when the vehicle was running normally:
http://www.bfimotorsports.com/matt/haltech/TRACK2.HDL

-Matt
www.bfimotorsports.com


PS: The intercooler is a massive greddy unit. (per Tim's question)

Okay, I looked at the trouble HDL file, and I found one nasty anomoly.
At 0:00:07.5, the RPM spikes to 7920RPMs, and that points to an ignition input problem.

What is your ignition input - trigger gain and home gain?
We've found that heat soak can induce CAS problems, so it is recommended to set them both to at "3".

Wow, your race data log is HUGE! I quickly scanned it, and gave up after page 200!

Is this set up for 3bar MAP?


-Ted

the rpm spikes can also be from interference or loose connection to CAS. I once had an ignition "problem" when the ECU was subject to excess heat it caused a complete shutdown. where is the ECU mounted? I found mounting it to another metal plate helped to dissipate any heat from the ECU and insulate it from any outside heat. stock location is not good on race cars, the exhaust is usually right under the ecu.

Yep, totally agreed with tims.
If the gain adjustment didn't fix it, that would've been the next step.

Check all wiring, especially the ignition input ones off the CAS.
Keep this wire away from the coil wires and the alternator as much as possible.

You might want to check and clean the CAS contacts (are you use the stock CAS plug?), as we've had all kinds of headaches with bad contacts especially with 89-91 versions.


-Ted

Yes, we are using a 3 bar map sensor.

Trigger gain and home gain are both set to "2."
The wiring seems ok and I'll try setting the gain to 3 and swapping out the CAS for another unit tomorrow night. We'll see what kind of difference that makes.

Thanks for your help. Its good just to have a couple more heads looking at things.

-Matt
www.bfimotorsports.com

Yes, we are using a 3 bar map sensor.

Trigger gain and home gain are both set to "2."
The wiring seems ok and I'll try setting the gain to 3 and swapping out the CAS for another unit tomorrow night. We'll see what kind of difference that makes.

Thanks for your help. Its good just to have a couple more heads looking at things.

-Matt
www.bfimotorsports.com

Yes, we are using a 3 bar map sensor.

Trigger gain and home gain are both set to "2."
The wiring seems ok and I'll try setting the gain to 3 and swapping out the CAS for another unit tomorrow night. We'll see what kind of difference that makes.

Thanks for your help. Its good just to have a couple more heads looking at things.

-Matt
www.bfimotorsports.com

I was also given a helpfull hint by one of the tech guys in Australia to use the Mazda OEM sheilded wire from the CAS to the Haltech harness and route it as far away from the plug wires as possible. I run mine across the front of the engine to the passenger side fender well and then connect into the Haltech loom. I am using the factory plug on the CAS, but all wiring is solder connected and wrappped with heat resistant wrapping. Haltech felt the OEM wire was of higher quality and provided better shielding. it is easily removed from the main harness. it is a large gray wire about 4 foot long.

Ground the haltech shielding wire in the haltech cas harness at the cas, and the misfires will probably go away, I had the same problem once..Max