digitaloutsider Posted February 24, 2009 Report Share Posted February 24, 2009 (crossposting this from the TGP forums to hopefully get some more suggestions) Hey guys. I finally picked up the new TGP, and everything's been great aside from one problem: When you're under heavy boost at WOT, sometimes it'll start pulling hard then hestitate/buck a couple of times and keep pulling again. When this happens, it almost sounds like a backfire/misfire and you can hear the boost rushing back out of the turbo as if you were railing on it and let off the gas. Frankly, that's exactly what it feels like. It doesn't do it all the time, and most commonly it happens around 75-80 on the freeway and right after a 2-1 downshift. Jeff M chip and x-over. The stock upper charge pipe to intake manifold coupler looked pretty ratty and had some big cracks on it, so I put an aftermarket one on hoping it'd cure some of the problem. It could just be a coincidence, but it seems to be doing it a little less, but it still happens. R42LTS plugs according to Luke. Not sure of the age of them. I'll probably get around to changing them just because. Heated AC Delco O2 sensor. I went over the vacuum lines and everything looks okay, couldn't see any cracks/breaks. Matt and I were talking about it last night and that it could possibly be the wastegate. Preferably, I'd like to change that as a last resort because, quite frankly, it looks like a major bitch to change Any other insight? (and ugh, i'm so close to turning TGP #1 into a parts car) Quote Link to comment Share on other sites More sharing options...
slick Posted February 24, 2009 Report Share Posted February 24, 2009 BTW, the vacuum line that needs work is the one right behind the intake plenum. You should be able to spot the 3.5 Intrigue patch (and the bottom of that is where the break on the hard line was, yeah... thats why I was going to just pull the plenum, but you may get away with just pulling the brackets off of the back of the plenum). Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted February 24, 2009 Report Share Posted February 24, 2009 The first thing I would do after having this exact problem countless times is pull the plugs and gap them. should be around .040, if any one of them is out at .045 .050 then you can't run a jeff m chip because the extra boost will blow out the spark. also if you have a boost leak you will get a similar condition. Jim's car had a coupler leak on his (turbo to IC)and you could actually hear it at first then it just ran like crap and the crossover started leaking. to me it seems overboost leads to the stock x-over leaking because his was fine before that. now there is soot by the flange. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted February 24, 2009 Report Share Posted February 24, 2009 thats not a parts car by any means. I could pull that dent without even painting it and DD it while doing upgrades to the other one. be boosted the whole time and smoke anything on the road pretty much. I'm greedy, I can't be NA for too long it gets depressing. so-- do check out the big long vac line to the map if slick says so, that was my problem many times until I just wised up and went down and bought out the parts store for all new vac elbows. No need to take off the bracket, what I do is undo the front dogbone brackets and rock the motor forward with a nylon strap to hold it. Quote Link to comment Share on other sites More sharing options...
slick Posted February 24, 2009 Report Share Posted February 24, 2009 No need to take off the bracket, what I do is undo the front dogbone brackets and rock the motor forward with a nylon strap to hold it. That will help, but it's like there is a mess of elbows going under and around the upper plenum and the bracket on the back of the plenum that supports the throttle cables. Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted February 24, 2009 Report Share Posted February 24, 2009 The first thing I would do after having this exact problem countless times is pull the plugs and gap them. should be around .040, if any one of them is out at .045 .050 then you can't run a jeff m chip because the extra boost will blow out the spark. also if you have a boost leak you will get a similar condition. Jim's car had a coupler leak on his (turbo to IC)and you could actually hear it at first then it just ran like crap and the crossover started leaking. to me it seems overboost leads to the stock x-over leaking because his was fine before that. now there is soot by the flange. You can gap them even tighter than that. With Kenny's Hot Tune, I am running .028" gap on the R42LTS. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted February 24, 2009 Report Share Posted February 24, 2009 yea, I know. I got a tweeked jeff m chip with 14 lbs of boost and will have to close the gap to at least .035. thanks for reminding me. but you are running them with less than .030? you have any issues with bad gas mileage or anything? other than the bad mileage we get with these cars anyway. Quote Link to comment Share on other sites More sharing options...
Addicted To Boost Posted February 25, 2009 Report Share Posted February 25, 2009 I haven't checked the mileage since I put in my new chip and did the tuneup. It seemed to get about the same mileage as before, but I really only did city driving, testing out the new K&N and BOV I'll have to take it on a highway trip sometime and let you know. Stock with the original plugs and wires on it, I averaged 31 MPG on the highway in the fall of '07. /end hijack Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted February 25, 2009 Author Report Share Posted February 25, 2009 Yeah, I'll buy a new set of plugs for it this weekend. I'm guessing that's the problem, the car is getting awful gas milage as well. (22 MPG on the way back from Ohio, granted I was getting it on it every so often, but nothing that should bring the average down that far) Quote Link to comment Share on other sites More sharing options...
slick Posted February 25, 2009 Report Share Posted February 25, 2009 Yeah, I was getting 31 mpg on the way back from Kansas. Something is definately up. You know what, I may know whats going on. I put Stabil in that tank of gas, since it was going to sit all winter long. That may be part of the problem. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted February 25, 2009 Report Share Posted February 25, 2009 I doubt the stabil hurt it Chris. I've put it in both my TGP's at one time or another and it's never made a difference in performance, mileage, etc. Quote Link to comment Share on other sites More sharing options...
slick Posted February 25, 2009 Report Share Posted February 25, 2009 Hmm.... that's really the only thing that I'd done to it then in the last 4 months, other than putting in the new carpet. I redid the heated O2 wiring probably no more than a month after I had the car, so it was still summertime. Quote Link to comment Share on other sites More sharing options...
GOT2B GM Posted February 26, 2009 Report Share Posted February 26, 2009 Gap Ac delco plugs at .028" - 0.030" New plug wires. I'm running my TGP with a Hot tune chip, ACD plugs at .028" Gets 30 MPG hwy. Runs 14.6 @ 95 mph on stock turbo & injectors. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted February 26, 2009 Report Share Posted February 26, 2009 I found out from Adam that the smaller gap has less to do with blowing out the spark and gas mileage. It's really for bringing down cylinder temps and less spark will keep the gas from burning as fast. which makes perfect sense, thats the same reason you buy 93 octane gas. Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted March 6, 2009 Author Report Share Posted March 6, 2009 Finally got around to doing the plugs. R42LTS @ .030". Runs amazing. Pulls like a bitch! Quote Link to comment Share on other sites More sharing options...
slick Posted March 6, 2009 Report Share Posted March 6, 2009 Fixed it??!!! Must get vid! Quote Link to comment Share on other sites More sharing options...
GOT2B GM Posted March 6, 2009 Report Share Posted March 6, 2009 Finally got around to doing the plugs. R42LTS @ .030". Runs amazing. Pulls like a bitch! I tell you no lies. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted March 6, 2009 Report Share Posted March 6, 2009 Pulls like a bitch! *cough* slow *cough*! Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted March 7, 2009 Author Report Share Posted March 7, 2009 It doesn't have the too-much-torque problem of the Regal, but it's still a fun powertrain. MUCH more entertaining than the L67, even if it is slower. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted March 7, 2009 Report Share Posted March 7, 2009 It doesn't have the too-much-torque problem of the Regal, but it's still a fun powertrain. MUCH more entertaining than the L67, even if it is slower. We give up a good bit of torque using the stock boost control, but you'll pretty much do nothing but spin with a manual boost controller. I've tried it and it's a night and day difference. My car spins pretty bad with the stock boost controller slowly ramping up boost... Quote Link to comment Share on other sites More sharing options...
shadow Posted March 25, 2009 Report Share Posted March 25, 2009 My 1990 tgp is having the same problem. It happened all of a sudden while i was on the highway a long while back. Is it easy to change the plugs on a tgp? I have big hands will I be able to reach them all? Thanks Chris Quote Link to comment Share on other sites More sharing options...
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