85 TPI 5 speed swap...Engine doesn't rev past 3800 now

[Alex89]

Alright, so to start things off I have been working on an 85 Trans am. When I bought it the guy that I purchased it from didn't bother to tell me that the 700R4 had a small leak. Consequently it got run down to almost no tranny fluid. Since then it acted like it was always dying and before the whole transmission went out I decided to swap it. I also have a 86 firebird doner car at home.

So I pulled all the parts I needed from the 86 to perform the transmision swap. New flywheel to match the 85's engine, reused the slightly used clutch (had replace it on the 86 not too long ago), and installed the 5 speed from the 86. Used the manual starter from the 86 (also semi new).

Now for the problem. The car doesn't like to run above 3800 rpm, nor will it run WOT. It runs rich and dies when you shift into idle. The previous owner had spliced the fan directly into the power wire for the distributor, which I have redone with a new relay. The timing was messed up so I pulled the distributor and moved it over a tooth to correct it. Basically something like this.

• Aftermarket distributor cap (not me but did check it)
• New plug wires
• New plugs (3rd set)
• Stock chip installed (had a tpichips aftermarket)
• 180 Deg thermostat (atleast it never goes above that)
• AIR system removed (exhaust manifold ports bent closed)
• A/C system removed
• Cat removed
• Cherry bomb exhaust installed (right after cat area)
• New Coolant temp sensor
• Some new vacuum lines
• K/N air filter & air foil
• New O2 sensor in the exhaust
• Sea foamed engine

I think that covers everything. I've adjusted the idle air and the TPS already and that helped my idle problem but it still exists.

The engine will not run above 3800 rpm unless you roll it up there. If you push the throttle in more that 75% it will struggle and go no where (Open vs closed loop?).What happens is the car seems to miss a lot. I'm attesting this to it running rich, I've already destroyed a few sets of plugs.
The car does not like engine breaking, it will die when you push the clutch in. I'm running out of ideas as to what to fix. Any thoughts anyone?

[MP81]

I'd like to add a couple things:

The fuel pressure is fine. We drove it with the gauge hooked up, and at full throttle it was right around 40-45ish.

We adjusted the idle (unplug ICS, adjust screw, reconnect, etc) and it seemed to fix the issue where it dies after engine braking, or it did at that point.

When the starter gets heat-soaked and won't start the car, it doesn't seem to like to run very well if you bump-start it...after a little while of giving it a bit of gas at idle, it'll be fine, but it is not happy when you push start it....

TPS is also adjusted correctly.

[JoeliusZ28]

the throttle body should not be "adjusted" if thats what you are referring to with the TPS. the adjustment is only meant to be a temporary solution if you are having a problem.

it definitely sounds like an open loop problem to me. This would lead me to believe that oxygen sensors are NOT the problem, but im going to against logic and suggest checking them anyway because of your other idle issues.

[Alex89]

What he is meaning by that is we adjusted the throttle position sensor (losened the screws and rotated it, checking it with a voltmeter) and went over the whole range to see if it was operating properly. Didn't seem to be an issue with it and I believe it was only off by a little bit.

[MP81]

Yeah, and we did that early in the process, I was making sure it was set to the right initial (at rest) voltage.

[WMCCjames]

Has the timing been adjusted? Are you getting any check engine lights? I get scared when I hear people say that the dist. was off a tooth.

[MP81]

We lately have been getting a random (very random and rare) code relating to the O2 sensor reading rich (we're aware it's super rich, as it smells like pure gasoline), but it's only done that once or twice. Otherwise no error codes.

Now, the timing seems to be rather spiky...like when rpms change, the timing REALLY changes...

[WMCCjames]

We lately have been getting a random (very random and rare) code relating to the O2 sensor reading rich (we're aware it's super rich, as it smells like pure gasoline), but it's only done that once or twice. Otherwise no error codes.

Now, the timing seems to be rather spiky...like when rpms change, the timing REALLY changes...

Was the timing set with the bypass unplugged? With the bypass plugged in, you will get vary erratic readings. This totally sounds like a timing issue to me. Unplug the bypass and set timing to 8 degrees if you guys haven't already.

[MP81]

The wire was not connected when we set timing. And I'm pretty sure the erratic readings were with it unplugged.

If it's timing (which it still very well could be) then wouldn't it sputter out at 4k rpm at 75% throttle too?

[Alex89]

We did set the timing using the bypass. Reason it was "a tooth off" I believe was the previous owner put a new cap on and by the quality of workmanship with his other modifications feel that he was at fault. The spark plug wires all had to be moved over one post to make the engine run, that is, timing was correct just each wire was moved one post counter clock wise. Made putting the new wires on difficult, so we fixed it.

[wasjo6431]

*shakes head* Timing then was off by over 20° if you had to move the wires to get it to run. set at TDC remove cap aka Turn the engine by hand to DTC where the rotor points is where Wire 1 is going to go. then adjust by 8 Degrees. If not check the springs in the Distributor. for the timing curve. Mechanical Or vacuum advance?

Edit: I personally have to set to 10-12 degrees to start the engine and back up to 18 to run it. at 800RPM

[MP81]

*shakes head* Timing then was off by over 20° if you had to move the wires to get it to run. set at TDC remove cap aka Turn the engine by hand to DTC where the rotor points is where Wire 1 is going to go. then adjust by 8 Degrees. If not check the springs in the Distributor. for the timing curve. Mechanical Or vacuum advance?

Edit: I personally have to set to 10-12 degrees to start the engine and back up to 18 to run it. at 800RPM

There aren't any springs - its an electronically controlled distributor - same for the advance - its computer controlled.

[wasjo6431]

gotcha gotcha. i shoulda seen that it was by the year. try resetting timing

[Alex89]

I'll check it again later tonight, but we have checked it a few times (with the computer unplugged) and at idle it is set to 6 deg. (6 deg was on the sticker). I'm starting to doubt it is a timing issue since I can get the car up to almost 5K if I roll the throttle up there. It only dies when I get on the throttle, anywhere above about 75%.

[jakes_GSXR]

dead spot in the tps?