Pinks All Out in a week. Can you help me get there?

[Sinister CO]

Okay, so I've been scrambling trying to get the GN together and ready for Pinks All Out on 8/8. I finally took it out for a test drive yesterday, and it seems to be backfiring on me. I've read quite a few posts on here and have checked the cam sensor, MAF, and all that fun stuff. I have not tried a new coil pack though.

Anyway, on to some info about the car. It has the usual fuel upgrades, Walbro FP, adjustable fuel pressure regulator, and hotwire. It has 60 lbs injectors too. I have a commander chip and the fuel pressure line off is at 45 (per the chip maker). The chip calls for one screen to be removed from the MAF, but I've tried it both ways and I may be crazy but I think it runs better with both in. It's got brand new plugs and wires on it. The plugs were gapped to .32 if I remember correctly. I also have a new oxygen sensor on it (purple wire GM). The TPS is .4 at idle and the IAC counts are in the twenties.

I hope that covers most of the info needed. I have direct scan too, so I've attached a couple of files from today. The first is in the garage, putting some revs to it in gear. The second is going down the block, backfiring quite a bit along the way. I'm not really sure what to look for on there, but thought maybe some of you guys will notice something out of the norm.

Any help you guys could offer would be appreciated. Thanks a ton!!!

By the way, I'll be out this evening so if you have any more questions about my setup, I'll get back to you tomorrow.

 

[Preston87GN]

backfiring out of the exhaust I have been told is usually the timing is on the retard side..maybe add a couple degrees of timing. if its in the intake try the opposite...goodluck

 

[wickedtt]

The module under the coil pack gets my vote!

 

[bmackinnon]

backfiring out of the exhaust I have been told is usually the timing is on the retard side..maybe add a couple degrees of timing. if its in the intake try the opposite...goodluck

SAY WHAT??? Clueless....Whatever..... anyway, backfiring under load/boost is usually either the coil pack or the module. Let me look at the DS file.... I'll get back....

 

[bmackinnon]

Hmmmmm... something is hosed up with the chip/translater combo.... likely the chip. Everything looks great idling, but all the blm's in cells 8-15 are sitting at 7 and 8?? They (the blm's) look fine in cells 0-7.... 128-132. Looks like the ecu won't even access the upper blm cells, so it's running in cell 7 - the highest one that isn't an absurdly low number. You should hit cell 15 pretty quickly just taking off from a stop. That's definitely your problem. Maybe need Bob Bailey to have a look.... or call Mike at Full Throttle.... it could be that the translator is set up wrong for the commander chip. Not a MAF translator guru here, but something in that regard is whacked.... perhaps someone a little more knowledgable has an explanation for crazy-low numbers in the upper blm cells.....

 

[bmackinnon]

Oh yea... I would recommend leaving both screens in the maf. It's my thought that some recommend using one, because alot of people are quick to just removing both. The screens serve to smooth the airflow across the sensor unit for a more accurate, stable, consistant measurement. I believe the airflow loss to be negligible. There were ALOT of dedicated engineering hours put into the calibration of the maf units.... JMO, of course.... And thinking further about the blm cells.... I guess the purpose of the MAFT is to effectively double the maf range... I'm wondering if this is doubling the increments in the blm table also... so possible explanation of no transition into the the upper blm cells??? Surely though, the answer to your problem lies in this area..... and if not.... MY second most likely suspect is still coil pack/ignition module...

 

[Sinister CO]

Thanks Brian!

I'm talking to Mike and Bob about the chip and also have a fellow Buick owner out here who's going to let me try his coil pack/module. Hopefully one of those solutions will get rid of this gremlin!

 

[XLR8]

Hopefully it will. I'll see you Saturday Jeff, hopefully we'll get it worked out.

 

[DavzGN]

I believe the extender chips used the 8-15 positions of the BLM to set parameters.

David

 

[TurboTnZ06]

I wish I still lived in Evergreen so I could make that race. I loved to whoop up on trailered "race" cars at Bandimere with my 126mph trapping Turbo T...Ah the good ol' days of 10,000 ft density altitudes...Good luck!

 

[TurboTnZ06]

SAY WHAT??? Clueless....Whatever..... anyway, backfiring under load/boost is usually either the coil pack or the module. Let me look at the DS file.... I'll get back....

Or the cam sensor is fubar. I snapped one once while it was running and it would only idle or go full throttle- Too bad when I got home I saw my oil pressure switch wires weren't plugged in...

 

[bmackinnon]

Or the cam sensor is fubar. I snapped one once while it was running and it would only idle or go full throttle- Too bad when I got home I saw my oil pressure switch wires weren't plugged in...

Yea.. true... cam sensor 180 out can cause problems too, and hosed up ring/window dohicky also.... but he said he checked the cam sensor, so I'm assuming it's set correctly and the guts aren't flopping around inside... :smile:

 

[bmackinnon]

I believe the extender chips used the 8-15 positions of the BLM to set parameters.

David

ahhhhh... :smile: Well, if Bob and Mike think the maft/chip combo is setup correctly, then I'm betting coil pack/ign. module....

Edit - check all them grounds too!! including the one on the coil pack bracket...

 

[Sinister CO]

Running out of options...

Okay, so Royal brought his car over this morning and we swapped some parts around.

We tried the coil pack/module, MAF, computer, and chip. The chip was actually for fifty lbs injectors where I have sixties. It was backfiring too, but being for a slightly different setup, I don't know if that was a valid test or not. We also checked the cam sensor again. Nothing we tried did any good and the cam sensor internals are all tight and it's set correctly. We unplugged the cam sensor after it was running and that didn't help. I don't know if I mentioned this originally or not, but it only backfires when it's under load. It idles fine and if I rev it lightly it's fine. A good heavy rev or actually getting it out on the road is when the backfiring starts.

I think that covers what we did today. I still haven't heard anything back from Bob on the chip.

Any other ideas??

 

[Sinister CO]

Not to leave you guys hanging, I just got my car back from the shop. The problem ended up being two wires that had broken loose from their connectors. One was on the ECM and the other was on the coil pack. I would have never figured that one out, so thank God for the guys at the shop!

Thanks for all the suggestions!

Jeff