....need some input regarding a driveability issue. I have done some research on the board and it has helped some. I have an 87 buick that starts to pop and backfire after about 30-40 mins (65-75 mph) of driving. It has an LT1 maf with a gen II setup using #60lb injectors. I've changed the cam sensor with a known good one with the same results. It also will not start if I unplug the maf sensor. If I plug it back in....it will start and really runs fine until I take on the road. However, if I unplug the maf after starting the car, it will cut off and not run. There are no codes and I have had it on powerlogger. Any advice would be appreciated....
...driveability issues!....
- Thread starter HNIC57
- Start date
Mine used to do the same thing after 30-40 mins driving on the freeway. Bad fuel pump in my case. I also suspect the hypertech chip I used to have had something to do with it until I upgraded to turbo tweak. New pump, chip, injectors, no more problems. What chip are you using?
...it's in my signature....the extreme "g" chip. As you can also see I have two gn's. I thought about the fuel pump along with the crank sensor; but the only thing that has me puzzled is the car cutting off when you unplug the maf. On the other gn that I have, when I unplug the maf, it doesn't cut off and the "check engine" light just comes on......not so on the gn with the problem.
You'll have to get that answer from someone else here but I don't think that's your problem. I'm not sure about an LT1 maf with translator but someone posted that the car should not start with the stock MAF unplugged. I had the same symptoms and after about 500 miles its stalled on me just close enough to cruise into a gas station. I thought my fuel gauge was acting up but after a few minutes it started back up and I drove home.
....alright man....thanks for looking.
- Joined
- Feb 18, 2006
Sounds ignition related. How old is your module? Did you try running in batch fire?
RL
RL
....I may eventually have to purchase a new coil & ignition module.....but let me tell you how I seemingly omitted that problem. As previously stated; I own two grand nationals. What I did is switched one with the other and the problem was still there......
turbo nasty
Turbo Dojo / MNTR
- Joined
- Jul 19, 2001
Whats your scantool showing during all of this?
well.....as I recall; all the reading looked normal with the exception of 02 readings. Whenever it popped and/or sputtered (backfired); the o2 readings leaned way down as if it was a fueling problem (part of the reason why I was thinking it could be a pump issue). If there wasn't this issue with the maf, then I would be leaning more in that direction. Anyone think it could be the crank sensor?......
turbo nasty
Turbo Dojo / MNTR
- Joined
- Jul 19, 2001
Whats your fuel PSI?
Whats your BLM's?
Whats your BLM's?
....went back and reviewed a couple of the files regarding this issue. As far as being definitive about the fuel pressure while driving I'm not sure. I have it set at 42#. The BLM's while driving at a steady cruise (75-80 mph) are INT 129 & BLM 119. To describe the issue according to powerlogger is this: when the problem occurs, the RPM's dip approximately in half (one occurence the rpms went from 2350 to 1175 and then back to 2325). Other changes during this exact moment are 02's go from .580v to .031v and then back up to 549; BLM's go from 119 to 122; MAF readings go from 51.2 g/s to 33.0 g/s and then back to 49.8 (although this didn't happen on every occasion). Don't know if this helps at all with diagnosing.....
williamsGN
'Horse sneeze' addict
- Joined
- Sep 20, 2007
Can you swap out the MAF for the one on the other GN ?
TheGovernment
Member
- Joined
- May 2, 2010
I bet it's the maf. I chased the same issue for 2 weeks and it was my brand new maf lol
....no I can't do the swap because one uses a LT1 maf and the other one is still stock for the time being. The maf is as good as a place to start as any. I guess I'm currently in the market for an LT1 maf. If that doesn't do it, then I'll go to the fuel pump. I would probably be a good thing to have these parts on hand if they don't turn out to be the problem. Thanks guys!.....
williamsGN
'Horse sneeze' addict
- Joined
- Sep 20, 2007
Have the stocker myself, but I believe you can pull the stock one off the other GN and put it in place of the LT1 and bypass the translator box and plug the original harness right in. I thought they were plug and play, unless there has been wires spliced.
.....yeah I spliced mine, I'm not sure if I can get the gen II to read the stock maf. I have to check but that might be an option. If not I'll have one on the way soon........thanks!
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