Question for those running Holley 3739 TBI (Page 1/2)
mckaymotoworks JAN 08, 04:20 PM
Once installed, was it plug and play or did you have to adjust the plug hidden fuel pressure? The documentation says that in almost all cases, no adjustments are necessary. I unplugged battery to reset the ECM per the documentation, but I have a high 2500 RPM idle in Park and Neutral. The first few days a stumble off stop, that seems to have cleared a bit, but I do notice it randomly still. It feels like the car is loading up on fuel then clears up with acceleration. Oddly, when first started, the idle starts at 1000RPM, but will climb after warming up or after being driven , or when in Park/Neutral. I thoroughly cleaned the intake area with throttle body cleaner and a brass brush.

This morning it briefly started then died due to the extreme cold weather, feels like the 02 code was tripped again, did it once before in cold weather with a brief start then dying. Something about a very cold condition triggers the false start and then one of the 02 44/45 codes. I'll verify this evening, just noting it's driving like it did the last time that code was thrown. Easily cleared by resetting ECM.

All my sensors are new, vacuum lines where tested and/or replaced, all connected. All the ignition system is new, timing was normal when last checked back in the summer. I did have a drift in the timing which I suspected was a worn distributor gear. I have yet to find time to replace the distributor.
mckaymotoworks JAN 09, 11:56 AM
Reset ECM, same rough start/bogging, once you break 40mph a few times, it seems to learn. Got it on the interstate, better, then the CEL came on, I increased speed, it turned off, came back on one more time before again turning off. I will check codes this evening.

The Park and Neutral high idle is still there. in Drive at a stop, sitting at 1100RPM

Another member who has the same TBI suggested the fuel pressure regulator sounds like it needs to be adjusted down. Documentation also calls for Kent Moore tool for IAC passage, I have no access to such.

Of note, fuel pump is new, I checked fuel pressure last spring at idle and under load, all new ignition minus distributor, when last timed, the timing seemed to drift every few revolutions (bearing?) we did jump ALDL ports during timing, and most every sensor is new. All replaced because the car sat for 17 years, not throwing parts at it, just working the gremlins out. I put the Holley on because the stock TBI was acting up and I had it, suspected leaky injector and replacement TPS was bad. It did resolve those issues.

It also died but started right back up yesterday, did that twice on a long trip, pick up coil suspected. I can get CARDONE Reman for a few dollars more than new pickup.

Now to figure out the new TBI tuning. Curious if the timing can't handle the additional fuel because the distributor is bad?

[This message has been edited by mckaymotoworks (edited 01-09-2015).]

mckaymotoworks JAN 09, 02:51 PM
Code 44. First time that code has been thrown while actually driving, it's done it once before in the driveway when the cold weather started when it briefly cranked, then promptly died. I can usually tell when this code is thrown by how it drives, hence me resetting the ECM last night

MAP is new, O2 is new, EGR is new. I have checked all the vacuum lines. Maybe the fuel pressure is set too low on the Holley TBI? I will check tomorrow.
mckaymotoworks JAN 09, 03:12 PM
I forgot to mention, when I first started the car, the header was glowing within a minute or too. Sounds very much like a lean fuel issue.
Of note, the Holley I bought was new in the box. The cap to adjust the regulator has never been touched. Maybe it was set to low when it left the Holley factory on 12/4/87. Will check this and other troubleshooting tomorrow.

Gall757 JAN 09, 03:36 PM
retarded timing will put a glow on the manifold too.....
mckaymotoworks JAN 09, 03:47 PM

quote
Originally posted by Gall757:

retarded timing will put a glow on the manifold too.....



As I stated here and in an older post, we check timing where it held but would "wobble" every so often. I can check the timing again.
Also of note, the alt belt squeals when first started since I bought it, other oddities associated with a bad alternator. Seem to recall it being tested as bad at auto parts store. Hard to remember, I have so many projects going, no to mention work. Just got reinterested in the Fiero while I await delivery of my CRX,

Car ran decent before I replaced the stock troubled TBI.
The original gasket had melded into the EGR track of the intake, was pretty nasty. Also suspected leaky injector. Had it on the shelf, solved a few of the issues.

All these new problems arose when introduced the new TBI. Trying to determine a logical approach to isolate where the issue is.

So far, symptoms are:
mileage decrease to 21MPG
High idle in Park/Neutral at 2-2300
High idle in Drive at 1200
code 44 ( new Bosch 02)
glowing manifold
car has mysteriously died a few times but restarts without further issue

[This message has been edited by mckaymotoworks (edited 01-09-2015).]

mckaymotoworks JAN 21, 09:30 AM
Back driving the car today, died a few times, but restarts and 14 MPG, ouch!. I will check the TPS that came with Holley TBI, I have my old one, test both with meter.
Check timing, adjust idle on Holley TBI, once the TPS and timing issues are ruled out, adjust the fuel pressure on the Holley TBI.
armos JAN 30, 02:06 AM

quote
Oddly, when first started, the idle starts at 1000RPM, but will climb after warming up or after being driven , or when in Park/Neutral.



quote
High idle in Park/Neutral at 2-2300
High idle in Drive at 1200


Sounds like some serious air is getting into the engine that shouldn't be. I'd normally think it's a vacuum leak somewhere, but if it starts at 1000rpm and only goes up after it warms up, then that sounds different. Unless the heat is what's opening up a leak.

What's the condition of the connector on your IAC valve? Is it broken up enough that it could be plugged incorrectly? It's a vague memory, but I think it's possible for the IAC to work backwards if it's pinned wrong.
ag9123 MAY 11, 10:48 AM
Any update?
ag9123 JUL 19, 03:19 PM
Did you ever get your drivability issues fixed?
I have a Holley TBI on my 84 as well.
It starts and runs fine but gets horrible gas mileage, around 12 mpg
Seems to idle well, has a 195 thermostat in it so I'm assuming it goes into closed loop
although I need to verify that with my scan tool.
I did adjust the fuel pressure regulator up a bit after I installed the Holley.
Not sure how to adjust the regulator without using an exhaust gas analyzer
Here are the tuning instructions from the Holley install doc:


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1984 Indy Fiero

[This message has been edited by ag9123 (edited 07-19-2018).]