Car pops no power at all!!

[87Buick]

Ok, so I have an 87 grand national that does not seem to ever wana run. Right now it idles fairly well until you get on the throttle. As soon as the engine is under load, ( no boost yet)she begins to pop. what is wrong?? Everyhing electrical is changed and gave it a better idle. What physical prob could it be if it was? Compresion is there, it's getting fuel, there is a new roller cam in it. Cam sensor is spot on. The cam chain tensioner is out, dont see how chain could skip. I just can't see how it could be the timing. Rocker arms are all working and the push rods are not bent. Just got done putting it together after a blown head gasket. And now this...The car has larger stock location intercooler, 3 in pipeing, Cai, 60 lb injectors, porter intake manifold, porter champion heads, 3 in downpipe, meth injection, roller cam, other than that, bottom end is stock.

 

[bmackinnon]

Dying fuel pump? Maybe (probably) that is what caused the blown headgasket? Does the fuel pressure rise lb. for lb. with boost like it's supposed to? What are the O2 readings? Or perhaps the maf sensor is bad? From your post, it doesn't sound like you have a clue about some of the imperative things you need to know about to own/drive one of these cars.... not trying to be an ass, but it seems you really need to start reading and gaining knowledge about the principles of operation of turbo buicks.... 'it's getting fuel' means NOTHING....

You need to hook up a fuel pressure gage with a hose that you can read while driving... tape it to the windshield if need be.... and note the pressure as you try to accelerate. The pressure should rise as you apply load. Also, while the engine is idling, try tapping on the maf sensor with a screwdriver handle.... if the engine stumbles/misses, the maf is bad.. Do you have a scanmaster/scantool of some sort? If not, you are shooting in the dark. If so, post up the O2 numbers when the problem is occurring....

and MOST IMPORTANTLY... do not try to run the car hard AT ALL until you get this sorted out.... or the pop, pop, will be your headgaskets blowing....again.....

 

[ijames]

Bad plug wires, coilpack, or ignition module, maybe crossed plug wires, almost plugged up fuel filter ... Do you know anyone close who has one of Casper's module/coilpack testers, with the spark gaps so you can check the wires too? If not it might be worth the $100 just to have it.

 

[87Buick]

Checked the fuel pressure. 43 lb at idle and continues to rise up and the O2 readings are good. Switched out the maf sensor, same pop. As for the plugs, they look and gap perfect. plug wires, and ignition are not bad either. coil pack tested bad, switched it out with a good one.

 

[bmackinnon]

So it's fixed?

Failing coilpack will definitely make it pop at boost... mine did it and it drove me crazy for a long time waaayyy back when... although mine wouldn't pop until it hit about 17-18 lbs... I would have mentioned that possibility, but in your orig. post, you stated 'everything electrical changed', which I took to include the coilpack/ign. module...

hope you didn't take my earlier post wrong.... just read it back and it sounded kind of ass-ish... no disrespect intended... :wink:

 

[87Buick]

Yeah I was hopeing It was that simple. Problem is still there however. Just idleing it's good but any Load or even reving over 2 grand pops.

It all happened while coming to a stop then giving it about 3/4 throttle. Boost was at only about 15lb. It made a distinct pop almost like when the cam sensor went out and threw the timeing off earlyer back. But when that happened it continued to get worse. Here it runs but like I said only under 2000rpm. Anything higher, there is a pop...pop pop.


Thanks for all the responses so far no disrespect. Thanks

 

[bmackinnon]

hmmmm... Did the car run correctly for awhile after the rebuild? Is the roller cam brand new? or was it in there before? Did you change the ignition module earlier with the new electrical parts? Were the heads surfaced as part of the headgasket r/r?

 

[87buickracer]

Ok, so I have an 87 grand national that does not seem to ever wana run. Right now it idles fairly well until you get on the throttle. As soon as the engine is under load, ( no boost yet)she begins to pop. what is wrong?? Everyhing electrical is changed and gave it a better idle. What physical prob could it be if it was? Compresion is there, it's getting fuel, there is a new roller cam in it. Cam sensor is spot on. The cam chain tensioner is out, dont see how chain could skip. I just can't see how it could be the timing. Rocker arms are all working and the push rods are not bent. Just got done putting it together after a blown head gasket. And now this...The car has larger stock location intercooler, 3 in pipeing, Cai, 60 lb injectors, porter intake manifold, porter champion heads, 3 in downpipe, meth injection, roller cam, other than that, bottom end is stock.

Recheck your timing/cam sensor/cam/crank sensor..a bad mass air flow sensor can make it pop and backfire...coilpack and module as well,have them tested..also check all your ground wires and make sure they are good,especially the ones behind the head..If you have a extra computer on hand,swap it out and try it..I see you changed injectors,make sure you have the right chip for your application..and make sure you installed the prom correctly..also make sure all vaccum lines are connected and good....make sure you have correct fuses in fuse box..
hope this helps..

ps--It sounds like a bad maf or timing off,had similar problem in the past..

 

[bmackinnon]

Checked the fuel pressure. 43 lb at idle and continues to rise up and the O2 readings are good. Switched out the maf sensor, same pop. As for the plugs, they look and gap perfect. plug wires, and ignition are not bad either. coil pack tested bad, switched it out with a good one.

he already checked/replaced the maf, found a bad coilpack and replaced it... good suggestion to verify the grounds on the back of the head... this has caused problems for many, and the heads were just off.... not a bad idea to give the ecm a look also... check for corrosion on the connectors, and verify the prom is seated correctly and no corrosion there either...

 

[whitehot1]

Have you taken a good look at the intercooler hoses to see if they are tight and one didn't blow partially off when you did that take off from the stop sign.

Check them real good especially if you still have the shorter hoses like the ones that came factory.

 

[bmackinnon]

Have you taken a good look at the intercooler hoses to see if they are tight and one didn't blow partially off when you did that take off from the stop sign.

Check them real good especially if you still have the shorter hoses like the ones that came factory.

another excellent suggestion... pop, pop, pop could be a hose relieving, or the car running like crap due to unmetered air coming in post maf... double/triple check that all are tight and fully engaged/in-place... you learn/remember SO MUCH with threads like this...

 

[87Buick]

Originaly over the past year or so the cam went bad, so I had a shop install a roller cam. Then shortly after the cam sensor went bad. Fixed that, the head gaskets blew. Took the engine out replaced the heads And gasket. Car ran well after, for a week. So the cam was replaced before the heads and the rebuild. All the grounds were checked again and are all tight and grounded properly. As for the coil pack, it was replaced while replacing all the other electrical the other day. Took it to a friends and he wanted to check the ECM too, even tho it was running fine a few days ago an it checked out good anyway. I'm going to try a third coil pack I have here because the one I replaced the first one with was my friends extra one. It's possible it could of just went bad? it orig checkedout good. It's the only thing I just have a feeling it has to be. If not the fronts coming off again and checking the cam chain.

 

[shifty6]

Did you also swap modules when you tried diff. coil packs?

 

[2 SLOW]

I have a friend who had a problem that sounds very very close to what you have. He had his motor rebuilt and ran fine for a short while. Then started running poorly. No one could be sure why it happened but this is what happened. The hub/balancer goes on the front end of the crank with a key in it to keep the hub from rotating. If the hub or key doesn't fit tight or the big bolt is not tight enough the play can make the keyway get wider. It did on my friends motor. This rotated the hub thus changing the timing since that also rotates the interrupter ring as well. His widened the keyway by about a half inch. That changed the timing by probably a good 25 degrees. He put a new hub on and the car has run fine ever since. It certainly could be something else but it sounds like you have checked just about everything else it could be without any success. Hope this helps and good luck.

 

[87Buick]

Thanks for that info. That is the next thing I am going to check, seeing that all else has failed so far.

Thanks for all the responses guys! We'll see where it goes from here...

 

[phirefighter515]

I have the exact same problem with my 87 T. I Changed the fuel injectors becasue one was sticking and the EGR Solenoid I found out was bad the whole time and now this problem started. I checked and changed the plugs, coil packs, and module. Nothing changed. All vaccuum lines are on and right. I am going to change the wires next because they are old but I don't think that is it. My car runs perfect at idle and up to about 3-5 pounds of boost and then it pops. Fuel pressure and O2 is good. I am now going to check all the things that are mentioned here. I just wanted to let you know that I have the same problem and if I find a fix I will post. Also if anyone can give me an answer. This may sound like a simple question, but I dont know. If the timing is off, would the car run like crap the whole time in this situation. I just can't figure out how it would have happened this quick.. It was basically running fine and then after bringing the car in to change the injectors and the EGR solenoid it started popping. And i do have the right chip in the computer for the injectors. I also changed the computer with a known working one.

 

[Double Deuce]

Did you check to see if the little tab inside the cam sensor is broken ? I worked on a G.N. last week with the same condition as your car and found the tab was partially broken. It didn't break off flush like they normally do. We replaced it and the car was purring like a kitten.

 

[2 SLOW]

OK, I talked to my friend again to get more info on just how his car acted with his problem. Here are some questions for both of you. Do you have normal vacuum at idle. Like in neutral 16-17 inchs of vacuum? He had about 10 inches. Does the car have the same power when starting normally from a stop? His was a dog. Does the car run hotter than normal. His ran hot all the time. My friends car had a big loss of power and as soon as he started from a stop the vacuum would go to almost zero. How severe this is could depend on how far the timing has changed. If the key has gouged the hub inside and moved it would be retarding the timing. So it would not be detonating.

Trying to avoid having either of you going to all the trouble of tearing it down enough to take the hub off. If it still looks like that could be it (and it isn't a given that it is) you might try to take the intercooler fan of and get a socket on the big bolt and loosen it and see if the hub will turn at all as it sits. If it does then you know where the problem is. Good luck and let us know what ever it is that is the problem.

 

[forcedfedv6]

Thanks for that info. That is the next thing I am going to check, seeing that all else has failed so far.

Thanks for all the responses guys! We'll see where it goes from here...

Is this you tony?

 

[87Buick]

No, this is mike