TPIJeep

Hello,

I retrofitted a Small Block Chevy stroker 415 cu in with a speed density TPI. The PROM has been programmed for the larger cubes, no EGR and the cam. It was set up for 24# injectors, when time came for the first start up I only had 19# units, when I cranked it after about 10 minutes the headers and some of the exhaust started to glow. I changed the injectors to 24# units hoping this would change the lean condition which I suspected was the cause, well it didn't. Here is what I have done so far, the injectors are 24# Accel units, I don't know what psi they are rated at but would assume they are stock replacments.

I unplugged the set timing connector and set the base timing at 8 BTDC and still had the glowing condition. I spoke with the shop who burned the PROM and they told me to plug the connector in and set the timing at 20 BTDC which I did to the best of my ability since the timing tab only went to 14 degrees. Well it still glows but not as bad, so I reset my min idle speed to 450-500 with the IAC unplugged and reset the TPS at .55v. This cured the VERY loud hissing coming from the IAC port but the headers still glow. Where should I go next, I am running 2.5" exhaust and 40 series Flowmasters which are brand new, also not running cats.

I also checked the fuel psi at the rail and at idle I have about 39 psi with the vaccum hose connected and when I unplug the hose it jumps to around 43 psi but the engine dies shorlty after unplugging it.

Please give me a hand with this I am at a loss.

Thanks

98_1LE

It is either running really lean, or the cats are really plugged up. I am guessing lean, what are the O2 sensor voltages?

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87 Formula 350 13.94@96.67
98 Z28 1LE 13.15@107.59
1LE Owners Association

JETHROIROC

Actually, I'm guessing it might be rich and the heat is a product of fuel burning in the exhaust system.

Replaced 19# with 24# no improvement...

415 motor with restrictive TPI to cut its air supply off...

Pulled vac. hose to increase the fuel pressure and engine dies...

Go back and reset the timing with the EST circuit bypassed. I can't begin to think of a good reason to set the timing with the computer advance coming into play. Make sure your ignition system is up to the task of igniting the fuel, and monitor your O2 sensor output to see whether it's lean or rich.

Smell the tailpipes with it running. Does it smell like gas? Does the oil smell like gas? Is the exhaust black and sooty?

The timing may still be retarded too far, make sure the outer ring on the torsional damper hasn't slipped. Are you using a streetdampr or is it just a stock replacement?

I'm thinking it's either too rich or the timing is retarded. Does the engine heat up quickly or just the exhaust system? If the damper is OK, these symptoms would make me strongly consider getting another PROM or burning my own. Let us know what you find, but I think we can help.

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1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, MSD coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Accel 23# injectors, Holley module, ported plenum,
Ported Daytona Yellow stock base, Moroso valve covers, other stuff,
Streetdampr, Ruger P95DC, hot wife, new oil filter, !cats, !TBC, !AIR.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

TPIJeep

Thanks for the info so far, there is a exhaust smell but I would not say it smells like raw fuel, no black smoke from pipes. With the EST unplugged and timing set to 8 BTDC the engine runs real rough the higher I get the better is runs. I checked the timing mark and it is at TDC so the ring has not moved, it is a stock 400 Damper.

Would it matter where the number 1 wire is in relationship to the sensors in the distributor. There is no mark on the cap which has to be the Number 1, I simply turned the oil pump shaft to point at the No. 1 cylinder and stabbed the distibutor so that the rotor points at the No. 1. If this matters let me know how things need to be lined up in relationship to the flat part on the cap where the harness plugs in.

How can I monitor my O2 sensor, what tool do I need? I am new to fuel injection, but am a old hand with carbed race engines.

Thanks

8Mike9

I'm with Jethro, it's rich...advancing the timing masks the condition...retarded timing allows unburnt fuel to be reignited in the exhaust.

If the headers were glowing up near the heads, I moght thing lean condition, but down the pipes and collectors cries of unburnt fuel, IMO.

RBMZ28

I m inclined to say it is lean.24 lb/ft injectors does'nt sound like enough.I and 2 other guys in our group have block learn in the 140 to 150 range(an indication of to lean ).hvae you checked it?btw all of us are running a small block 400.30 lb/ft (based on
formula i have recently found)I also suspect the chip was not calibrated properly.once again,2 of us in the group are using t.p.i.s
chip(custom).we also have the same problem
(headers getting red after revving/holding
rpm for a while.go on the diy site for more info on these so called custom chips.

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87 IROC WITH 409(.040 OVER400) MINIRAM,NOS(125HP)TRICK FLOW PORTED HEADS,C.C.CAM,FLOWTEK HEADERS,CUSTOM PROM,MODIFIED 700R TRANS,2400 B&M CONVERTER,3.73POSI REAREND.
LOOKING FOR THE 11 SEC. ZONE.current ets.12.39@114 mph

kevinc

There are different harmonic balancers for SB Chevies, and they have the TDC mark in different locations. Did you change the balancer during the build?

If you're running a mismatched balancer & pointer for your crank, the timing will be off considerably.

Double-check your parts, if in doubt swap back to your old known good balancer and re-check the timing.

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1982 Z-28

See http://www.mycar.net/mafb/registry/detail.cfm?id=276 for details

GeneralHazzard

ok i had this happen on a buddys s10 with a 355. its timing retarded way too much. gas is igniting in exhaust. on his it was that the distributor internals were froze up. another friend had the prob the guy said earlier about balancers and tabs being mismatched. i think the big balancers had it in the middle, and the small ones could be either left or right. check these things, cause i really think it sounds to me the timing is way late. and i thought stock timing was like 6btdc? 20 sounds kinda off. kinda really off.