problem won't go away.....

[gn84guy]

hey all
Finally got my knock and boost gauges hookes up, and put a new maf sensor on the car and im still having a problem of a stumble under throttle, and a kinda rough idle...And what confuses me more is that im only getting 4.5# when i floor it and at one point it lit up three green lights on the knock guage....I have no idea whats going on with this car so any suggestions would be very helpful! Could this be a bad injector??? Is there any way to check for this? Also, I have already replaced the coil and ign mod with the 87 conv.

thanks again
Robert

 

[buickpower]

have you checked for vacuum leaks? Sometimes they can cause those symptoms.

Mike

 

[Jerryl]

Do you have an aftermarket boost gauge and a scan tool?

 

[gn84guy]

checked my vac lines and they all seem to be nice and solid. I have and aftermarket boost guage but i do not have a scantool yet...which ones are directly compatible with the hotairs? And I took it out today and i really think its probably an injector...is there a good way to check to see if these are good? Thanks for the help!
-Robert

 

[buickpower]

You can test injectors by plugging an injector test light or "noid" light into where the injector itself would normally plug in the injector harness, and check to see while cranking if it is getting power. You would do this for all 6. Also you can put an automotive stethoscope on the injector while running and listen for the clicking to verify it is working. Please note that injectors can be physically working but clogged as hell and barely putting out fuel. Maybe try running a can of good injector cleaner and see if it helps any.

As far as your vacuum lines, check to see they are all connected and to the proper places, reverify with the diagrams in the stickies at the top of this forum. You can't tell by a visual if they are bad normally, as the holes are often tiny. If you have a vacuum pump or know someone that does, use that to see if all the individual lines will hold vacuum, and do it one at a time so you put them back in the right spot. If you don't know someone that owns a pump and dont want to spend the 35 bucks on one, it is much cheaper to just replace all the lines with new hose, one at a time. A cheap thing to replace, and even if they are not the cause, they will just last that much longer anyway. HTH

Mike

edit: btw, what does the "54000 rounds" mean in your sig?

 

[buickpower]

Almost forgot, if you are only getting 4.5psi, it could be a potential exhaust leak, which could also cause some of your symptoms. Check the car while running for cracked headers at the point where the three primary tubes join together, that is a common thing with these cars. Also, if you can, check the two header to crossover pipe connections for leaks. I carefully listen near them for ticking or hissing and sometimes put my hand in the area to feel for any pulses, but don't burn yourself . What octane gas are you running and how many miles on the car?

Mike

 

[Bryan C.]

Also, check to make sure you do not have a plugged catalytic converter.

 

[Jerryl]

Good advice Buickpower and Bian C!
I was eluting to some O2 readings with the "scan tool question" and wanted to be sure you are not using the stock boost gauge as an indicator of boost levels. (I should have paid better attention to your writings in the original post regarding the boost gauge )

Also, make sure you have adequate FP. I did not read in your sig that you replaced the fuel pump (?) One injector may be bad but, without FP and O2 readings it is hard to say (??)
Did this “low boost” started suddenly or did you change something when this all started?

 

[gn84guy]

Thanks for all the imput! i guess ill have to take a day and go through and replace all my vac lines cause it is a pretty easy thing to do, and it probly is a good thing to do on a twenty-one year old car. As for fuel pressure i forgot to mention that i tested that earlier, and it did everything it was s'posed to. And as far as to how long I've had this low boost problem...I really dont know because all I've had up until i posted was the stock boost guage that i dont trust at all. I really hope that when i fix this stumbling problem the low boost goes away...but if it doesnt i guess i will have to search for an exaust leak next when i get the car running right.
Another question i have is what scan tools are directly compatible with these hotairs and where can i get them?
thanks again
Robert

 

[gn84guy]

OH and i forgot to add that the car has 55000 miles on it, and that i run the highest octane gas i can find which is usually 92 or 93. I also think my headers have been replaced by the previous owner because then look like new.

 

[Bryan C.]

As far as scan tools go, TurboLink is your only option with the stock computer. It does not provide much info(with the hot air computer), but it does help. Your best bet is to change to the 86-7 ECM and then DirectScan, TurboLink, or ScanMaster will provide the info you need. With the ScanMaster you are limited on recording and storing your info though. I would suggest DirectScan or TurboLink. HTH.

 

[FJM568]

Check your turbo to intake adapter o-rings and make sure they are okay...

You were the one that had the major backfire, right??? Did you check the turbo to throttle body gasket for tears??? Also, look at the vacuum block gasket and make sure that the vacuum hoses aren't split...Physically, pull them off and look closely at them...Don't just eyeball them while they are connected...

 

[BRAD_PADGETT]

A agree- check the turbo to intake gasket for a leak. I have this problem right now. Use carburater cleaner and spray around the gasket while the car is at idle. If the idle changes you have found your vacuum leak. Also, I bought an OTC 4000 scan tool with the 1980-1983 chip on ebay for $130-Avoids the laptop cost and size. Works great. Brad-1985 GN with 85 ECM.