This is about a 1984 2.8L Carburated V6 Firebird, new cat as off 5 months before this started.
While idling/ running with the clutch in, it runs great, revs all the way upto redline no problems. When there is the slightest load on the engine, it bogs down big time. It takes a couple of minutes to hit 3000 rpm and shift into second, a couple more minutes to hit 3000 rpm and go to third..at which point that is all there is. I can hit about 25-27 MPH and that is it. No codes at all. It SOUNDS like its muffled when its bogging down, but the cat is a brand new Catco high flow cat. THe fuel pump was replaced about a year ago from pontiac itself as the old one was leaking fuel. This issue has been getting worse for over 2-3 months. In feb I had to buy a new car as I couldnt afford to repair the bird. Well now Im ready, and need help tracking down the issue. Any suggestions for what to do?

Also, how can I check the cat to ensure something is not clogging it up? The smog line is welded in so I cant recall just take it off.

EDIT: I did replace the cap/rotor/distributer/coil/plugs in feburary before I had to give up on the car..so those are all new as well.

Thanks for any help guys.

 

Something is holding back your timing or it is not advancing at all, by computer.
WHAT I WOULD SCORE IS another ECM from a FWD vehicle of your year.
Next is see what is happening durng acceleration as in your timing and distributor.
Other option is to check all your vacuum hoses.
Do you still have a smog road map?
This should work for ya....

 

Karl, if that's the diagram off your blazer, unfortunatly I don't think it's the same as for the F-bodies, good idea though.

Where in California?

 

That's a 1982-1984 F Body smog sticker.

My 85 Blazer smog sticker is totally different, as I have a 49 State, Federal Version, 2.8, automatic, Blazer. And I do have the smog sticker for my vehicle, too (took me a while to score it, tho!!)
California Blazers, tho, is "probably" identical to the F Body, I'll bet.

That sticker attched is a 1982-1984 F Body.
IF I am correct or IF I recall, that is a California smog sticker, too (I have since sold it).
IF I AM CORRECT, tho, all 50 state F body 82-84 smog stickers should look like the example.

 

Thanks Karl, I DO have the smog/Vacuum hose diagram in my, haynes I think, that or the GM manual, or the chiltons.. one of them has it. But I dont hear any noises like a vacuum leak. Ill have to check again though.

I have to ask though why would a FWD ECU help to diagnoce this? I do have a second 84 firebird computer, and the issue is the same with that one.

I am at work right now but I think I have the WinALDL output from a trip to work, bout 20 mins of data. I can post the info from that tonight I think.

I dont think its anything with the distributor as that was totally replaced with no change at all in the issue.

A friend suspects fuel starvation, so he thinks fuel pump or carb himself.

I jus know I only have the weekends an not much cash to work on the bird right now. Ah well least you have given me a couple things to look at.

 

2_point8_boy: I live in the Sacramento area.

 

The FWD ECUs are the same as in your Firebird/Camaro. You simply keep original PROM when checking on an ECU problem. I offered that IF ya had no spare for any testing.
Ya generally won't hear any vacuum leaks on these cars. It's a hose that's aged and the eye/hand/fingers find it easier than the ear.
If your distributor was recent then check wiring to the distb. for "weakness".
The pump pressure on these 2 ESE rides is so small...like 5 PSI.....
I also still say to check alternator, as power is necessary as the RPM increases.
And again check all vacuum hoses.
The timing is computer controlled, something is holding back timing and a signal to a "relay/solinoid" can also come from vacuum issues.
Other thing can be,
ready,
collasping fuel line hose, as need increases, the hose, gets sucked closed.
IF ya feather the gas to gain speed, this situation may not occur.
Keep working at it...

 

Oh I plan to work on it
Okay at work, reading the boards today, dont get home till 11PM. Thinking from the baords, that I may need to replace my timing chain, no I havent done that yet.

The Distributer was replaced to try and fix this issue, was thinking it might be electical. The Alternator appears to be fine, throwing out about 13.8V as I recall. I dont think its a collapsing fuel hose as the problem is always there, WOT or just barely working the gas...there just is no acceleration.

Okay so the work for tomarrow morning is vacuum leaks and check timing chain/timing...what fun

And as for the amps on the alt...It is under a year old, and is the largest, at 100amps, that is possible for the 84.

 

I had an alternator that was tossing out high voltage spikes which fried 6 ICMs before I deduced it was the alternator causing the problem. Replacing the ICMs was wasted effort until I found the cause of them burning up. My alternator was a freshly expensive rebuilt unit, too, as in who would suspect?
Vacuum hoses is a bear to search and hope that all are fine. I ended up replacing all or 90% of mine on my Blazer due to why not? It was easier to solve any leaks, this way.
Chain, do the test as I mentioned and give a shout. Bet you'll see slop.
Hope these are good clues.

 

Okay ya the timing chain appears shot. I can get in a good 1/2 turn or abit more before the rotor moves..so timings off cause of the chain.. Beh well there goes my 3 day weekend
Now to find what parts I need and who has em locally...

 

Dynogear is the chain to use
I'll get part numbers
It's $30-ish
Number 73042
Also get a Fel Pro timing chain gasket set
AND new water pump & double check hoses.
Also score this other item a balancer sleeve repair kit. It removes the grove in the balancer from years of usage.
Pioneer #14908 or HB-4127-S
or
Fel Pro brand 16212 or 21-2512 or 970109

I got all my stuff at Pep Boys
By time ya done the engine will be stronger, run cooler & also get better gas milage.
It's a win-win job.
WHEN ya do this job BIG CONCERN IS the timing chain cover & any internal wear from corossion of cluids.
MAKE VERY SURE you T chain cover is in very good shape.
IF too aged internally, it will wear thru & fluid will escape.
I know I was stranded by a worn T chain cover. I had water gushing out like Niagara Falls!
Bottom hose outlet is the place to check.
AND to remove t chain you have 8mm bolts at front lip of oil pan accessed from bottom of car.
THEY ARE FINE THREADED MACHINE THREADS BE VERY VERY secure in your re-tightening of them so as NOT TO STRIP the t chain cover!
PS LOTS OF CLEANING right now is key to good job.
ALSO GET a TENSIONER!!!!
It's important also. That item MAY be dealer item or part counter. It is important to replace this item also.
Planning is the key to this job.
Imagine that this job never done so lots of worn items of which to now repair, one time.

 

Rad/hoses/water pump was all replaced last summer so its all good still. I will double check, but a few months shouldnt wear that out. Thanks for the part numbers, Looks like I might be able to get that all from Autozone here, now just hope the balancer isnt in need of replacement as well, that is a special order, could take weeks to get one.

EDIT: DOnno bout the tensioner, doesnt show one at all for the 84, starts in like 85 though...maybe something new the MPFI cars only got.

EDITEDIT: Okay its a dampener not a tensioner...it looks like it stops the chain from flopping inwards, but doesnt tension anything...ya that probly needs replacing as well

 

New little funny....why is it ALL the auto shops say timing chins do not strech and never need to be replaced unless it skips a tooth?

 

Answer, tell them to buy your car as is, then drive it.
They'll be replacing the chain, too.