FITECH 39001 low idle cannot adjust up
I am having issues with the idle on my vehicle. I have programmed the idle to be 850 when hot. Unfortunately the Fitech 39001 never reaches this speed. When hot it idles around 550 to 650, whilst this is low it is ok when hot. What is not OK is when the vehicle is cold - 550 to 600 and it dies constantly, letting it warm up for a few minutes it will cut out when decelerating or pedalling off to slow for traffic, lights etc. It also hesitates and stumbles occassionally when warm and you accelerate hard. Other than this the engine runs smooth, pulls really well and drives basically very nicely. Just the idle and cutting out is frustrating. I have not driven the vehicle more than 10 or miles at a time due to these issues.
The engine is;
Make: GENERAL MOTORS HOLDEN
Cylinders: 6 inline (Red Motor)
Capacity: 202 cu in or 3.3 litres
Ignition: Electronic HEI
Intake: Redline 12-65M - MANIFOLD 2BBL FIT HOLDEN 6 CYL - with a Trans-Dapt Performance Carburetor Spacers 2134 to clearance airfliter over rocket cover.
Exhaust: Advanced Headers - oxygen sensor mounted approx 8 inches aft of collecter
Camshaft: Stock
Cylinder head: small skim and upgraded for running on unleaded
Fuel supply: Command Centre 2 Part No: 40004
As part of the installation of the system;
all new gaskets have been used,
all new stainless exhaust system fitted,
headers ceramic coated,
All new fuel hose and fittings
New thermostat fitted
New PCV fitted
Initially the vehicle would not start, this was identified due to broken fuel nipple connector on the out side of the fuel pump. I repaired this and once the fuel command 2 was delivering pressure to the Fitech 39001 the engine started and ran. New pulp arrived recently but I have not fitted it yet.
The vehicle required slight open throttle to start and idle. The idle was low and remained low even when hot. When cold the engine would idle for a short period at approx 500 rpm and then cut out, once warmed up it idles but very low.
The IAC reading showing mostly 0 occasionally jumping to 4 or 3 but straight back to 0. TPS at idle = 0. I tried turning in the idle stop and resetting the TPS by key off and on method - IAC still mostly 0 with similar jumps as before. Could not get the 7 - 10 I read about.
The vehicle still requires slight opening of the throttle to start.
I removed the throttle body spacer and tried mounting the unit directly to the intake manifold but this did not improve the issue. Still needs slight open throttle to start and no change in the IAC numbers. I increased the base warm idle setting to 1000 rpm - no difference.
I re-installed the carb spacer and the low idle issue persists. I turned in the throttle stop screw until the TPS = 1. Key off to set to 0. I started the engine but still the idle is low, but the IAC is now 140 ish. Turning the screw out slowly the engine dies before the IAC goes below 130.
I checked timing again once the vehicle is warm up - Temp = 188F. And I lean out the AFR at idle from 14.5 to 13. The vehicle idles at approximately 675 - 750 but not consistently. It changes erractically.
I allowed the engine to cool and the low idle is still there 500 ish.
I have checked thoroughly for any vacuum leaks and cannot identify any.
What guidance do you have for addressing this issue?
Thanks for help and guidance
Do you have a exhaust 12-18 inches past the O2 sensor? I have seen this before when exhaust is not installed or there is an exhaust leak pre-sensor.
Hi, yes there is a full stainless steel exhaust.
Considering I had checked everything, I threw the baby out with the bath water and decide to ignore the IACs and set the idle the good old fashioned way. I simply turned in the idle stop until I got the idle I wanted with the engine at operating temperature. The vehicle idled and drove once I did this. IACs were not happy though - 124 to 150 and it was temperamental when starting and sooo over fuelling.
I zeroed the TPS, reset the tune to out of the box. The vehicle ran very poorly and way too much fuel. This is so frustrating as I know the engine is good as it was perfect on carburetor.
I read around on the internet and found that the Holley instructions are very specific about the switched +12v - clearly stating DO NOT /NEVER use the coil supply for this. The Fitech instructions say do not use the coil supply if using an external ignition box. As I don't have an external ignition box this was my source.
I rewired this feed (white wire) to get the +12v from battery routed through a switched relay. I relocated the temperature sensor to sense water temperature in the cylinder head and reset the learning to factory setting.
The vehicle starts better, release the key and straight after start the idle goes to 1150 ish then drops to 700 - 800 (set at 750 on the hand controller) in 2 - 3 seconds, hot or cold and the IACs are now between 3 - 9 occassionally I see a 10 or 11 but the majority of the time its 3 - 9. The vehicle does drive very smoothly except there is no engine braking now.
The rpm hangs, will stay up around 1200 - 1400 when you throttle off and slowly returns to the idle speed. When the vehicle is parked it does the same. Rev the engine, clean no bother, but the decel is very very slow taking several seconds to return to idle.
Seems I have swapped on issue for a different one 🙂 any pointers on how to get it the rev and decel clean?
Thanks
Increase your loop rate down value in your idle control settings. Try adding in "10" increments. This will solve the slow dropping idle.
Glad figured out your problem...
Thanks for the tip. I ended up adding 20. The idle does come back better, but the last bit is still slow to drop to the actual idle set.
Rev the engine and the revs drop smartly to approximately 1100 then slowly returns to the 750 setting. I went to +30 but it didn't seem to make any difference over the initial +10.
Is there something else I should be adjusting?
Let it learn....
Hi, just back from approximately 150 km drive - self learning, my unit must have a learning dificulty; I don't think it could have passed kindergarten! This has to be the most frustrating, unreliable, unpredictable and erractic "fuel injection" there is.
I started a drive this morning, with the issues mentioned above, but the vehicle drove. At around 80km (50 miles) into the drive it started. Idle was all over the place when you came to a stop. The thing hesitates when you try to pull away, it floods then, it cuts out. Wont start, then will start, blows black smoke drives but only at constant throttle once you nurse the thing over 5 miles an hour.
I managed to limp/nurse the car home. I even tried resetting the tune on the side of the road, made absolutely no difference. I had to push the car up the drive when I got home. It is like tap, jazz and ballet dancing on the throttle to even get the vehicle to move off. It will then drive fairly smoothly but if you must throttle off for any reason the vehicle hesitates, floods, revs, dies - if I could guess how it will behave I should by a lottery ticket.
Really really really fed up with this system.
The only thing at this stage assuming Fitech 39001 units are not complete unreliable wastes of money, is that the O2 sensor has failed for some reason? Would that be plausible? I will see if I can get a replacement 02 sensor, and if that does not cure the nonsense then the only fix I can see is to buy a Sniper unit or go back to carbs.
I tried to data log but the car wont even stay going long enough now to get anything useful, 4 or 5 starts to just pull away from a stop - it's a juggling act to get the vehicle moving to a point it will stay going and I could get home.
Thank you for the pointers to date, and any future help you can offer.
Oh God, I feel for you, brings back memories of what was going through my mind. My race motor with only 5" Hg vacuum was a real challenge getting running right, and it is much better now. For me the first step was to look at the plugs to see how black they were, and they were black and wet. It was running way to rich at idle especially, and I had to set my idle AFR to 16.4 to finally be able to idle it for extended period. For each iteration of the AFR change, I had to take the plugs out and clean them until they finally looked good. You won't have to go to an AFR of 16.4, unless you have only 5" Hg of vacuum. Once you get it idling and up to temp, you can start looking at other things like setting your IAC steps, etc. Hope this helps.
Hi, thanks for the comment. I have 16 - 17" of vacuum. The thing just will not lean out and runs so rich now. I would say fat, but obese would be a better discription.
The real kicker is that it actually started to drive so nicely. Then all this nonsense with idle, dieing, reving, overfueling. Any adjustments I make are made with the temperature over 160 - usually 170 to 180. I have brand new E3 plugs, new leads - I have given it every opportunity to do its thing and "learn" but I think mine is mentally challenged and incapable of learning anything at this stage.
I have ordered a new O2 sensor and if that doesn't cure it - the next purchase will be a Holley Sniper.
The point of my post was that you can't run plugs when it's too rich, you need to lean it out until plugs look good, unless you enjoy the car running like crap. You're right that the O2 sensor may be the problem if you can't change your AFR setting to get the plugs to look good.