The Stovebolt Site Forums The Shop Area The HiPo Shop TPI mounted on 327 - working out some bugs

Still trying to workout a few bugs on my truck. I have TPI mounted on a mildly built 327. I've only driven it a few times but here are a couple of problems I've encountered:

1. Misfire in 1 & 2. I've checked the wiring and can't seem to find any shorts. Thought the injectors may be clogged so I put a couple of bottles of injector cleaner in the tank.

2. Front brakes mysteriously locked up while driving. (suspension is a '79 1/2 ton IFS)

3. When coming to a stop the engine surges and Wants to accelerate.

Any ideas?

Vacuum leaks? A lean burn condition at the front of the intake causing misfires and a idle problem? Just thinking out loud,
Scott

Robert..I'm not too sure about the engine bugs,but are your brakes getting so hot to the point they are binding?
Or did they just lock solid?
Can you give some more info on the brakes?

I'd just installed the electric fan and had taken it out for a short drive. I noticed that the engine seemed like it was running under a load & when I got off the gas pedal the truck would virtually stop. I noticed it appeared to be smoke coming from the wheel wells and sure enough, the brakes were smoking. I let it sit for a few moments to cool off and drove it home and by the time I arrived it appeared to be driving fine.

Im just throwing stuff out here, I think some seems logical.

were you on the brake at all when they locked up? maybe a kinked hose holding pressure or something??? Maybe a pad coming loose and catching the rotor? did both brakes lock up or just one?

Are you running o2 sensors and the mass air sensor. If they've been remove than your ecm needs to be recalculated to run open loop.

As far as the brakes go are you running a residual valve in the front brakes? Mabe the push rod is to long and keeping the brakes set to tight to the rotors.

Just some thoughts.

My brakes did that same thing due to "heat" from exhaust pipe being to close to the master cylinder, causing the fluid to expand, maybe?

Scott, I'll check for leaks, thanks.

Chris, I don't recall being on the brakes at the time but boyh sides locked up.

Wilber, I do have the 02 sensor and map sensor in place and the ecm is calibrated for both.

Yakimabowtie, my MC is on the firewall away from the headers.

I agree with wilbur on this one Robert,it sounds like you've got too much residual pressure in the brake system somewhere.
Do you have a residual valve in the front circuit?
Is it a new master cylinder? If you used the original Drum brake M/C and now have discs,it could be the M/C is mismatched to the discs.i.e the M/C has too much residual pressure.
Or...as wilbur said you have a wrongly adjusted pushrod.
Just some things to check.
Good luck
Jock

Mobileortho, I was refering to the mass air flow sensor, goes between the throttle body and the air cleaner. Your irratic idle could also be the idle air control. It's located under the throttle body, they get carboned up and need to be cleaned.
Do you have the serial port ( obd 1 plug under dash ) so that it can be scanned?
The master cylinder needs to match the front brake application. For example, my front disc' are camaro so is my MC. Check for a pinched brake line going to the front, like to tight of a bend or kink.

Just thinking out loud, hope this helps.

Thanks, Wilbur for the tip on the idle air control. I think you may be on to something. I'll check it out this weekend. As far as the MAF sensor, I don't use that setup. I'm running speed density which uses a MAP sensor.

I do have the serial port but there is not indication that a code has been tripped. I got a key from Autozone awhile back so that I could get the codes without the scanner.

I have talked to you before and you have an early speed density FI unit like I have as I recall (early IROC, no MAF sensor). Now, I'm only guessing based on my experience:

The surging when you come to a stop could be a problem with the speedo not telling the FI that the vehicle is stopped. You should have a yellow and purple wire connector conversion device on your trans where the original speedo cable connected. The two wires go back to the ECM and tells the ECM if the vehicle is moving or not. The solid wire speedo cable wire is also connected to this electronic device and goes back to your speedometer as originally configured. Now, I think you may have changed the original speedo unit to an electonic one, but that doesn't change things and still means you must have input from the trans via the 2 wires to the ECM. The other problem I had with mine, which kind of sounds like your surging problem, (mine would stall, not surge) was a fuel pressure problem. Not enough fuel at a constant pressure. Put a gauge on your fuel pressue and see when you gun it that it holds the pressure. It should hold about 42 lbs. There is a fitting on your FI unit rail where a gauge can be installed. I solved my problem with an expensive external Edelbrock fuel pump made specifically for FI. If your fuel pump is in the tank and is a later corvette type for FI, then forget what I just said. All this is guess work, but I want to see all us FI guys succeed.

JOCK:
Do they have opossums in the UK or just possums?

Yep, it's an earlier unit converted to run speed density. I do recall the wires you mentioned that run to the tranny. I'm purchasing a converter from Jags to hook them up. I also noticed that the idle air sensor is loose. Will see if those two things are the cause of the surging.

Don't know about the fuel injection problem , but normally with that disc brake system you need to replace the flexible rubber lines to the calipers .

The lines are new.