i have a 1986 gn with a whopping 166,000 miles on it. i know, alot. however this car was my grandfathers and thats the reason i chose to try to restore her. i have been working on this car for the past three years and i still cannot get her to run properly. keep in mind the car is 100 percent stock, only has a shift kit installed. the car violently bucks and backfires under boost. it will only make it up to 8 lbs of boost before this starts to happen. let me tell you everything i have replaced so far... new spark plugs, wires, coil pack, module, fuel pressure regulator, lt1 maf sensor, maf translator, all new vacuum hoses and lines, new boost gauge, new alternator, battery, fuel pump, fuel pump hanger, hot wire kit, adjustable boost actuator, among numerous other exterior and interior items. from discussing this problem before, many people have told me many possible causes of this problem ranging from the cam sensor to the maf sensor to module and coil pack. i have tried the trick of unplugging the cam sensor when the car is running to see if it runs better and the car runs way worse after i unplug it so i dont think that could be the cause. and seeing how i replaced the other items i dont know where to go next with this. also, the fuel pump that i installed is ridiculously loud, you can hear it whinning from really far away, is this normal? im just trying everything i can to find whats wrong but i feel that i replaced close to every single part on this car to no avail. if anyone has any ideas it would be much appreciated. i will even give you my personal cell number if you would rather call me than type, just PM me. Thanks a lot guys, i really appreciate any input because like i said before, i am really close to just calling it quits and letting someone else deal with it. Thanks again
pretty close to just calling it quits and putting the car on craiglist....
- Thread starter 86grdnatl
- Start date
measured fuel pressure while driving? considering you say that the fuel pump is really loud it makes me think there is something wrong there.
where do you live, there may be someone nearby that can lend a hand.
a worn out cam will cause backfires/popping at WOT.
the car should run almost the same with the cam sensor unplugged, so somethings amiss there.
what injectors and chip?
Bob
where do you live, there may be someone nearby that can lend a hand.
a worn out cam will cause backfires/popping at WOT.
the car should run almost the same with the cam sensor unplugged, so somethings amiss there.
what injectors and chip?
Bob
TurboTnZ06
Go on red!
- Joined
- May 7, 2002
Pull cam sensor cap and see if the metal ring is loose or spins by hand. It should not wiggle about. There is a special procedure to set the cam sensor position by measuring voltage on the voltage window opening on the hall effect sensor of it and going 1.45 inches past tdc on #1. These cars are love or hate, no in between.
Hopefully the stock plastic timing chain has been replaced correctly.
Hopefully the stock plastic timing chain has been replaced correctly.
thanks guys, i live right outside philadelphia, PA and ive been talking to few professionals that said they would be more than willing to look at it and troubleshoot it. which is what i think i am going to end up doing. but i have no accurate way of measuring fuel pressure when driving....my fuel pressure gauge recently broke. but ive been told before that my car is running rich. i was also told by jim dunn that because my cam sensor has never been replaced or removed that it is a long shot in being the cause. he told me that a wrong reinstallation could cause problems, but mine has never been removed or adjusted. i have the stock injectors that have been in the car forever and the chip is stock as well (to the best of my knowledge). i know ishould replace them, but i dont know enough about which ones to get or how to install them. turbotnz06, if my cam sensor has never been removed, could it be a problem? and yes fuel pump and fuel filter are new.
TurboTnZ06
Go on red!
- Joined
- May 7, 2002
Friday I was ready to burn my car too. (Cam sensor ring was loose, then broke). Sunday, 10 minutes after fixing it at the track with another one, I ran 10.54 after driving it 57 miles to the track.
I've snapped the cam sensor roll pin (it drives the oil pump off a gear on the cam as well as provide a sensor on that shaft). When that pin goes, the car may start just out of luck on that sensor working, but then it goes into batch fire mode if it gets lost, then backfires ensue. If you can spin the metal cap thing, either its broke there or the pin on the shaft broke, The pin may also be broke and jammed it up in the wrong position too. I wouldn't pull it out unless you mark where the window is and then get it back in (pita btw since you need a screw driver to rotate the oil pump slot back enough to make the sensor drop in the same since it spins when you pull it out)
The tiny stamped metal tab on the cam sensor can break as well. It's a poor piece of metal and I think RJC sells a kit to make it better.
Is it hard to start? The cam sensor tells the computer where the cycle of the cam is so it can start. After it starts, it runs. It can be loose too causing this. I just went through this on my car. The metal part cracked, wobbled about and would start, then move around. When the computer then asks where things are, it was say 10+ degrees off, enough to make it run terrible and slight backfire under load or a complete spark miss.
When the pin on my cam sensor broke on my old engine, it would idle fine, then backfire like no tomorrow under load and not accelerate. Of course, that pin being broke means no oil pressure since it's not turning the oil pump.
Plus pulling that cap off is an easy check that is only moving the intake tube out of the way and a couple phillips screws to get to that cap to eliminate that.
Plastic timing teeth have been known to jump the chain since you may only have 3 left on the gearset.
I've snapped the cam sensor roll pin (it drives the oil pump off a gear on the cam as well as provide a sensor on that shaft). When that pin goes, the car may start just out of luck on that sensor working, but then it goes into batch fire mode if it gets lost, then backfires ensue. If you can spin the metal cap thing, either its broke there or the pin on the shaft broke, The pin may also be broke and jammed it up in the wrong position too. I wouldn't pull it out unless you mark where the window is and then get it back in (pita btw since you need a screw driver to rotate the oil pump slot back enough to make the sensor drop in the same since it spins when you pull it out)
The tiny stamped metal tab on the cam sensor can break as well. It's a poor piece of metal and I think RJC sells a kit to make it better.
Is it hard to start? The cam sensor tells the computer where the cycle of the cam is so it can start. After it starts, it runs. It can be loose too causing this. I just went through this on my car. The metal part cracked, wobbled about and would start, then move around. When the computer then asks where things are, it was say 10+ degrees off, enough to make it run terrible and slight backfire under load or a complete spark miss.
When the pin on my cam sensor broke on my old engine, it would idle fine, then backfire like no tomorrow under load and not accelerate. Of course, that pin being broke means no oil pressure since it's not turning the oil pump.
Plus pulling that cap off is an easy check that is only moving the intake tube out of the way and a couple phillips screws to get to that cap to eliminate that.
Plastic timing teeth have been known to jump the chain since you may only have 3 left on the gearset.
If you're still on the stock timing set and it's jumped a tooth, the cam sensor setting will be off. Even if you haven't jumped a tooth yet, that set needs to be replaced. They only last a little over 20 years or 150,000 miles and you're just over both of those.
Since it's necessary preventative maintenance, I'd go ahead and get a stock timing set, tentioner, roller cam button, gasket set and an oil pickup. Then set aside a nice weekend to pull the pan and timing cover, drop the pan, change the pickup, do my oiling mods, inspect the cam sensor, and put it all back together.
Best case, the car will start acting right. Worst case, you'll take care of a grenade and know the timings correct, and have better oiling.
Since it's necessary preventative maintenance, I'd go ahead and get a stock timing set, tentioner, roller cam button, gasket set and an oil pickup. Then set aside a nice weekend to pull the pan and timing cover, drop the pan, change the pickup, do my oiling mods, inspect the cam sensor, and put it all back together.
Best case, the car will start acting right. Worst case, you'll take care of a grenade and know the timings correct, and have better oiling.
There are a bunch of guys in the Philly area and if you post in the northeast section I'd bet 1 or more of them would be willing to help you for little or nothing. Not to mention the NJ and NY area guys. The state/area section is further down the main page and if you haven't gone that far down it's time you said hi and see what happens.
- Joined
- May 28, 2001
Check the crank end play.
Check the balancer to see if it's cracked.
Check to see if the crank sensor is properly spaced, and not being eaten up by the ring.
Check the balancer to see if it's cracked.
Check to see if the crank sensor is properly spaced, and not being eaten up by the ring.
Pronto
Believe nothing you hear and half of what you see.
- Joined
- Dec 9, 2002
That's a lot of miles to the timing chain/nylon gear. I'm voting it jumped a gear. As far as the pump goes, put a fuel pressure gauge on it and drive around if you aren't getting pressure to raise the pump is probably defective. What pump is it? I friend replaced his stocker with a parts store one and it was junk.
Much good advice here. What I would do is first determine whether you want to keep the car. Ask yourself if you'd keep it if it ran well. If the answer is yes, then take a break from it for awhile, then Start with a clean slate.
Check the free and easy stuff first that you may have checked multiple times already. Plug wires in right order, translator settings correct, coil pack and ignition module wired correctly, those sorts of things. Pull the vc's and check that all valves are opening and closing. Verify the cam sensor is set correctly and not 180* out. Verify cat isn't plugged. Verify fuel pressure isn't falling off. Re-check the new pump and hanger and hotwire. All free stuff and only cost time. Change the fuel filter?
If you have no "aha" moments then, proceed to the stuff that probably needs to be done anyway - scanmaster, timing set, checking to see if it has jumped a tooth on the sprocket, injectors and chip. I'm assuming you still have stock chip and injectors. Don't be afraid of the injectors, they are very easy to replace. Just keep in mind that the chip must be matched to the injectors.
I wish you luck with your grandfather's TB. These cars are a blast when they run right. They will drive you insane if they do not.
Check the free and easy stuff first that you may have checked multiple times already. Plug wires in right order, translator settings correct, coil pack and ignition module wired correctly, those sorts of things. Pull the vc's and check that all valves are opening and closing. Verify the cam sensor is set correctly and not 180* out. Verify cat isn't plugged. Verify fuel pressure isn't falling off. Re-check the new pump and hanger and hotwire. All free stuff and only cost time. Change the fuel filter?
If you have no "aha" moments then, proceed to the stuff that probably needs to be done anyway - scanmaster, timing set, checking to see if it has jumped a tooth on the sprocket, injectors and chip. I'm assuming you still have stock chip and injectors. Don't be afraid of the injectors, they are very easy to replace. Just keep in mind that the chip must be matched to the injectors.
I wish you luck with your grandfather's TB. These cars are a blast when they run right. They will drive you insane if they do not.
You should be money ahead if you take it to a "Buick Guy" and you pay him hourly. Otherwise if you try selling it the way it is, you won't get much. Of course if someone can help you for little or nothing, that would be the best route. Good luck and let us know what you find out.
MauDeuce50
Need Rehab for Boost Addiction
- Joined
- Nov 28, 2013
I think the whining noise could mean that there is a lot of build up in the gas tank. I recently had the same noise and i took it to the shop and there was a lot of gunk in the gas tank. I had the tank cleaned, filter replaced, and a new pump put in and that put an end to that annoying whining noise.
The pump might just be installed without a sleeve, Loud is not a sign its bad,
There are only so many parts so It can be fixed. I just fixed a 87 for a shop in Maryland they tracked me down somehow. similar to your car. they had 2 issues, cam ring had moved ( common) and they had the plugs gapped at .60 kind of a 2/1 but had it straight in a hr.
They had replaced cts, tps, maf, map ,computer, prom, crank sensor, cam sensor cap, timing chain, fuel pump,fuel filter, injectors, vacuum hoses, plugs wires... guess what none of that fixed it.
I have had many Meaning at least 8-10 cars act like yours with weak coils, (yes brand new and bad ! ) the key is knowing how to break the systems down and test the components in a orderly and timely fashion.
Wire harness with hi resistance... all kinds of wacky stuff happening now that they are getting up there in age.
If you can't get someone to get it right bring it by one Saturday and I'm 100% we can get it correctly diagnosed in short order.
There are only so many parts so It can be fixed. I just fixed a 87 for a shop in Maryland they tracked me down somehow. similar to your car. they had 2 issues, cam ring had moved ( common) and they had the plugs gapped at .60 kind of a 2/1 but had it straight in a hr.
They had replaced cts, tps, maf, map ,computer, prom, crank sensor, cam sensor cap, timing chain, fuel pump,fuel filter, injectors, vacuum hoses, plugs wires... guess what none of that fixed it.
I have had many Meaning at least 8-10 cars act like yours with weak coils, (yes brand new and bad ! ) the key is knowing how to break the systems down and test the components in a orderly and timely fashion.
Wire harness with hi resistance... all kinds of wacky stuff happening now that they are getting up there in age.
If you can't get someone to get it right bring it by one Saturday and I'm 100% we can get it correctly diagnosed in short order.
chris kirk
Active Member
- Joined
- Jun 1, 2013
Dale Cherry @ Injection Connection. 135 Horsham Rd, Horsham, PA 19144 (215) 675-8515
Sound like my exact story. After 4 years of trouble shooting, 2 sets of head gaskets, etc, it ended up being a wiped lobe on the cam shaft. Replaced it with a 206 comp cam and its been running great. Mine has 150k miles on it. I now run Rotella 15-40 with ZDDP additive. I also went with a stock style metal gear set and new timing chain.
