Noob needing help, not building boost and backfire

[wile2k]

Guys and gals a bit of help please,

86 T-type.

Car was running fine a couple days ago. I got on it passing a car on the freeway, one time it was fine, next time I heard a bit of a popping in the exhaust just as I began to enter boost. Now that is all I get, right as I should be starting to spool and build boost, I hear a little popping through the exaust and it doesn't spool.

If I push it, it will build boost erratically and if I really push it it will backfire. I have a scanmaster, but I'm pretty new to the car so i'm not sure what I should be looking for on it.

When not in boost the car behaves very nicely, it idles smooth and accelerates smooth up until about 40% throttle when it should be beginning to enter boost. I pulled the intake pipe and the turbo feels ok, it spins smoothly and doesn't seem to have any play in the shaft.

I really dont know where to start with it, please keep in mind that I'm pretty new to Turbo Buicks, so I might need a bit of babysitting. Right now I'm thinking electrical (MAF, crank sensor, coil), but that it doesnt build boost properly really has me worried.

Help appreciated.

 

[gndoug]

My guess would be a flat cam. Big issue with these cars.

 

[TURBOELKY]

um um

look into a set of good head gaskets, and put in some arp head studs while your at it. is'nt life great?

 

[sixnboost]

Hey,
I would inspect all of your IC connections. Chances are you blew one loose.
Remember to start out with simple stuff first.

 

[gndoug]

Come to think of it.. I would guess its the motor. You should just buy a stage block. JK!

 

[TURBOELKY]

yeah

start small, he's right. Could even be a vaccume leak, bad ignition, bad maf, then do a compression check. Probably your head gaskets good luck man.

 

[wile2k]

LOL, guys breaking in the new guy right eh?

If it was head gaskets, would it not build boost anymore? Same question for cam?

It was spooling at about 1/3 throttle, nice and smooth when it was working right, and now I have to go well past 1/2 to get any boost at all. I'm going to check the IC hoses, that seems logical, although, I would think that if I blew a hose, it would not build boost at all.

Oil and coolant looks ok, so if I blew a head gasket it would have to be from the cyl out and I dont see anything like that.

If I wiped a lobe, wouldnt the car idle and run poorly even off boost? Basically in vacuum, it runs fine, it is only when I get into boost. I'm going to check the MAF as best I can, really seems like it is having a fueling / ignition problem, but again, it strikes me as odd how poorly it builds boost if that is the case.

Any other ideas appreciated.

 

[TurboBuRick]

LOL, guys breaking in the new guy right eh?

If it was head gaskets, would it not build boost anymore? Same question for cam?

It was spooling at about 1/3 throttle, nice and smooth when it was working right, and now I have to go well past 1/2 to get any boost at all. I'm going to check the IC hoses, that seems logical, although, I would think that if I blew a hose, it would not build boost at all.

Oil and coolant looks ok, so if I blew a head gasket it would have to be from the cyl out and I dont see anything like that.

If I wiped a lobe, wouldnt the car idle and run poorly even off boost? Basically in vacuum, it runs fine, it is only when I get into boost. I'm going to check the MAF as best I can, really seems like it is having a fueling / ignition problem, but again, it strikes me as odd how poorly it builds boost if that is the case.

Any other ideas appreciated.

First things first. Post all scanmaster #s
No it will not build boost if a headgasket is blown or cam is flat. Cam lobe may just have enough to still lift the valve a little bit and the car would run fine down low. Its when you try to move big volume through the valve you see the condition. Lobe will eventually go completly flat and it will miss all the time. Not just up high trying to boost but in vacuum as well.
Flat cam lobe is a common thing on TR's. You could pull the valve covers and check rockers for movement. Start on the drivers side becase 9 out of 10 it's #3 exaust valve.
Scanmaster readings may get you some other possibilitys but from what you describe it souns like flat cam, just like gndoug said in the first response.

 

[Razor]

Hole in IC, loose turbo or IC hose..

Initial guess.

 

[JRNYMNDAVID]

Hole in IC, loose turbo or IC hose..

Initial guess.

IC[??] DEF PLEASE..

 

[TurboBuRick]

AHHHHHH, Inter Cooler.

 

[wile2k]

Hole in IC, loose turbo or IC hose..

Initial guess.

Well, I might just be in the inital stages of denial, but I'm going to look first to the IC or IC hoses. The more I think about it, it seems like it is just losing the boost somewhere. I sure hope it isnt a cam lobe, would it be at all odd that it is working one minute and dead the next? That is about how sudden this came on.

I appreciate the responses...

 

[TURBOELKY]

here ye here ye

with one whiped lobe, the car will still build boost, with a bad head gasket, it will still build boost until the point where it cannot hold that ammount and back fire the boost out of that bad area. He said he was passing a car on the freeway, the next thing he knows its popping. My buddys car had a bad head gasket do the same symptom. But that is the worst case scenerio if that is how its spelt probably your ignition though, check the ignition module and coil pack out, try to get one from somebody who has a known good one, see if that solves the problem. Good luck, and let us know what you find. oh yeah, is the check engine light coming on?

 

[sixnboost]

When I first posted last night about the IC hoses, I was speaking from my epeirence with this. I went down the road and got on it and it was feeling good and all of a sudden I heard a loud pop and good feeling went sour.

I could barely get the car back to my shop it was running so bad. I thought I had done serious damage.

When I popped the hood everything looked normal at first then I noticed the hose. The clamp was still there but the hose was kinda cocked sideways.

The cheap clamps will distort if too tight and cause them pop loose.

Get some T-bolt clamps and forget about it! Also check all the hose connections all the way from the turbo to the intake not just IC.

 

[wile2k]

with one whiped lobe, the car will still build boost, with a bad head gasket, it will still build boost until the point where it cannot hold that ammount and back fire the boost out of that bad area. He said he was passing a car on the freeway, the next thing he knows its popping. My buddys car had a bad head gasket do the same symptom. But that is the worst case scenerio if that is how its spelt probably your ignition though, check the ignition module and coil pack out, try to get one from somebody who has a known good one, see if that solves the problem. Good luck, and let us know what you find. oh yeah, is the check engine light coming on?

I checked all the IC hoses and they all seem good. Can't check the IC itself until I can get the front end apart (fmic). As it sits now, it will not build even 1 psi without some light popping, it literally will not let me get past 1/2 throttle under normal load. If I'm stupid and just mash it to the floor, I can build plenty of boost, it is just really rough in building it and it doesn't feel right.

What would the symptoms of ignition failure be, or weak ignition?

What would the symptoms of MAF failure be?

I checked the coolant and oil and they dont seem cross contaminated.

I'll go for a ride and watch some scanmaster readings. Any specific ones that I should be looking for?

Thanks...

By the way, no check engine light on....

 

[TURBOELKY]

yup

I too popped off an intercooler hose once, I did'nt have it tight enough. as far as weak symptoms on the coil pack, there is a way to check it with a volt ohm meter. You will have to do a search on that one. Or i'm sure somebody will post how to check it. The symptoms you have now are a bad module or coil, the car will run, but does not have the spark the engine needs to combust the air and fuel you dump into the cylinders at open throttle. Go through your scan master till you see the mal/nal if you have a 2.1 if there is a number there post it... also maf failure is pretty much the same symptom as you have now also. You would most likely get an error code on that one for sure, but you never know. As far as the oil and water not being cross contaminated, head gaskets dont only blow one way, they could also leak compression, but not water into the oil. You probably dont have a bad head gasket, just trying to scare you...

 

[TurboBuRick]

I checked all the IC hoses and they all seem good. Can't check the IC itself until I can get the front end apart (fmic). As it sits now, it will not build even 1 psi without some light popping, it literally will not let me get past 1/2 throttle under normal load. If I'm stupid and just mash it to the floor, I can build plenty of boost, it is just really rough in building it and it doesn't feel right.

What would the symptoms of ignition failure be, or weak ignition?

What would the symptoms of MAF failure be?

I checked the coolant and oil and they dont seem cross contaminated.

I'll go for a ride and watch some scanmaster readings. Any specific ones that I should be looking for?

Thanks...

By the way, no check engine light on....

Poping still sounds like the cam went flat to me but lets see all the numbers.
It could very well be spark related also.

 

[wile2k]

Poping still sounds like the cam went flat to me but lets see all the numbers.
It could very well be spark related also.

Rick, I really do appreciate your time and comments, even if I dont want to hear what you are saying lol. I hope that it is easier than cam, but if not, it is a good reason to get a roller in there.

Anyway, you asked for numbers, can you tell me what you would like to see. Keep in mind that I can't go over about 1/3-1/2 throttle before it starts breaking up on me. Also that I only have a scanmaster at this time.

I'm going to go out now and check the key off and idle numbers for any irregularities.

 

[TurboBuRick]

AF
TPS
IAC
BL

Grab the numbers in park @ idle and motor at full temp.

Coil Tower Resistance
(measure front to back, on top) 11K - 13K ohms
(for each of the 3 towers)

 

[Brer Rabbit]

My vote is module/coilpack

with one whiped lobe, the car will still build boost, with a bad head gasket, it will still build boost until the point where it cannot hold that ammount and back fire the boost out of that bad area. He said he was passing a car on the freeway, the next thing he knows its popping. My buddys car had a bad head gasket do the same symptom. But that is the worst case scenerio if that is how its spelt probably your ignition though, check the ignition module and coil pack out, try to get one from somebody who has a known good one, see if that solves the problem. Good luck, and let us know what you find. oh yeah, is the check engine light coming on?

Im with the Turboelky, it seems like theres a coil pack and module Gremlin jumping from car to car lately. One buddy(Lil Chip Foose) had to swap his out before the big meet in Iowa a few weeks ago cuz his was cracked and he powersprayed the motor and water got up into the coil. Mine went bad right before the same trip, and my other buddy Wrath is going to pick up a module and coil pack as I type this. The symptoms tend to vary when it starts to go bad. In my case, My car would start to loose fuel pressure after the car was normal operating temperature and after about 10 miutes of driving. $260.00 later for all new delco parts and no problems since. The Wraths car wont build boost over 11 or 12 pounds but pulls pretty good up to that point, just like u described. Heres the bitch about testing the module, I took mine to Murrays and he tested it and told me it was fine, the test cant simulate the heat under the hood or the 10 minute drive before failure, so dont rely on the test process. I would certainly borrow a known good one and Ill bet ur car has no more problems. If U go Delco like I did try GMpartsdirect.com That should be the cheapest around on the parts. Dont forget the 4 dollar gasket between the coilpack and module.