2_point8_boy

we'll start with the problem...My car now lacks any ***** that it had at one point, makes A LOT of noise(I attribute that to the fact that one of the exhaust manifold bolts is working it's way out, and it misses/surges throughout the driving range, but is mostly ok above 3K.

I have already replaced the coil, I've had 3 go bad on me, so I thought it would be a good investment whether that was the problem or not. I also made sure that all of the plug wires were on nice and tight. All of the ignition system has been replaced within the last 6 months, so hopfully that isn't where the problem lies. New fuel filter and air filter's as well. TPS is new and adjusted perfectly at 0.55 v at idle with a smooth raise to 4.5 at WOT. No codes either. On my way home from work the car ran perfectly, but then i went to the store only like 30 minutes later and now it's like this.

I am going to fix the exhaust leak tomorrow and am planning to adjust my valves since I have the day off. Also going to soak the plennum in cleaner to make it nice again. Cap and rotor are coming of for inspection anyway. Timing is dead on 12* BTDC.

Is there anything that you guys suggest I look into besides the normal tune up things. Thanks in advance.

Jeff.

KED85

Definetly the exhaust intake leakage can affect performance.
YET I think...
It could also be the fuel line ya used.
It may be kinking or collasping under pressure of engine demands. This happened on my old Opel Sport Wagon w/FI. I used wrong gas line when I replaced my fuel filter.
It collasped under the engine load & I couldn't get above 30 either!
Fuel injected cars require Fuel Injection fuel line hose.
It could also be electronics...
The alternator may be failing & not giving enough juice for the situation.
Hope these are some leads for ya.

TomP

About soaking the plenum.... don't re-use the original gaskets. Buy a roll of thin black gasket material (like $2.99 at a parts store), an x-acto knife, a hole punch (kind you hit with a hammer, usually for making holes in leather), and a block of wood, and cut your own NEW gaskets. Re-using old gaskets can lead to vacuum leaks.

Felpro sells an upper intake kit for $30 with new TB and plenum gaskets- but it also comes with the lower-plenum-to-intake-manifold gasket, EGR gaskets, intake-manifold-to-heads gaskets, and valve cover gaskets (cheap cork), so the price doesn't really justify buying the kit just for 3 gaskets.

Karl's right about the exhauast leak, fix that first. I'd say to roll through the major tuneup list afterwards and see if that fixes anything. Yes things have been replaced but check the parts out- i.e. ignition: check gap on plugs, clean the cap/rotor from carbon tracking, check resistance of plug wires. Check important sensors for corrosion (tps, maf, mat). Do the "wiggle test" with the harness wires at the distributor- if the car stumbles while you wiggle the harness wires back and forth, you know there's a problem there. And definately check the fuel pressure with a gauge; it can point you to a failing pump or a failed regulator or a leaking injector.

2_point8_boy

I fixed the problem!!! Funny how a vacuum leak can ruin how the car runs. The line that runs to the Air Pump melted to the EGR valve and clogged. Form what I figure is that the motor was pulling a vacuum when it clogged and it got the valve to stay open and keep pumping into the exhaust stream. With the extra air always going down stream to the O2 sensor and the exhaust leak not letting more exhaust go to the O2 sensor, it thought that there was a lot of extra oxygen and running lean, so it pumped more gas into the engine and bogged it down...now that the Air Pump is working right again the car runs great. BTW, I took the little coke can muffler off the air pump and now it sounds really cool, kinda like Dowards BOV should sound like.

2_point8_boy

J/K, I thought I fixed the problem, but now it's intermittant. Sometimes if I get on the gas real hard it kinda sputters until about 2K, then runs fine, also if it sputters and i get off then back on, it's fine too. Weird huh? Fuel pressure was dead on 42 PSI at idle. sounds about right, I didn't have time to check it while revving because I got called into freaking work Anyways...let me know what you guys think.

KED85

IF original fuel pump,
It's fuel pump.
That's exactly how my Firebird reacted.
It's beginning to fail.
Finding vacuum leaks was a big help, too.
Did ya make sure any wires to close to hot exhaust source?
IF ya on Westside, I got a shop I can offer for great work.
He's in Santa Monica on Lincoln Blvd by Pico but really Closer to Ocean Park. AND GREAT Mexican food right by his shop so ya won't go hungry while the job is being done. AND ya have saved some repair bill cash by doing the fuel filter work!
From this repair shop, it's 15-20 minutes walk to Venice Beach, "The Zoo", too.
Give a shout if this may help ya.
Yeah, I know, an honest mechanic in LA, CA!
I like that, "The Governator!"

2_point8_boy

You know what i think it is, my pressure regulator...or vacuum line connected to it or something. I have to look at the diagram, but I thin that the decel valve/Air Pump are connected to the same feed line. It's gotton a lot better, but I'll have to break out the fuel pressure guage and vacuum pump again to check.

KED85

All that is inside that pressure regulator is a spring & a rubber diaphram.
You need a special torq socket to get in there.

2_point8_boy

yeah, I don't think it's the regulator itself, but somewhere in the vacuum line that is leaking. What happenes is if I step on the gas the motor kinda bogs for a moment, then it picks up fine. Starting vacation tomorrow...parents are paying for fiance and I to go to Disney World for a week, so it'll have to wait until I get back.

Project: 85 2.8 bird

tps and/or the MAP sensor?