Potential solution for all those struggling with Hesitation, bog, Lean Tip in, hunting idle, stalling, stumble, IAC steps
Hi everyone,
I am very new to the Fitech systems I have a EFI GO 600 with PA on a slightly modified Pontiac 400.
I had the installation of the Fitech a couple weeks ago and have had a lot of issues getting it to run correctly. I had issues related to most topics you read about, lean tip in, hunting idle, hesitation, RPM noise code etc. but the really weird thing was that every day I got in the car it seemed like the tuning I did the day before to help solve the problem no longer worked. A good example is the IAC steps. I would get it set around 8-10 at temperature and it would be fine, then the next day it would run like crap so i would go and check it and the IAC steps would be at 50, it just didn't make any sense.
Today I looked at some logs from yesterday and noticed that my MAP value seemed locked so I started searching for bad MAP sensor etc. and ran across this thread.
https://fitechefituning.com/fitech-efi-tuning-forum-2/topic/bad-map-sensor/?part=2
I took the gasket off cut it as instructed (almost completely get rid of the stem of the gasket) and reinstalled, I didn't even unbolt the Fitech from the car. Started it up and took it for a 10 mile drive - not one issue with lean tip in, hesitation, idle issues the car ran amazing and performed beyond what I was expecting.
If you haven't tried this yet and are going crazy with the lean tip in, hesitation or idle issues, it is worth a shot and takes about 10 minutes. I really think the Mods should sticky the linked post in the tuning section as it is such an obscure thing to mess with.
I really hope this helps some others get their system working how it should.
Just came across your post last night, tried it this morning and my car is running right for the first time in 3 weeks!
We have changed distributer, plug wires ....thrown money at it, still ran like shit. Sliced off 1/8" of rubber and car is a running great! Now I can actually look forward to driving it! 67 Gt500 convertible recreation, 351 W with T-5
Thank you Thank you Thank you!
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Just to clarify, are you seeing the problem as a stuck vacuum/MAP reading or is this also happening when you get varying readings?
Also, can you clarify where is the MAP sensor, or which bolts have to be losen to test?
Awesome! I am so glad it helped out, I did the same thing changing random stuff hoping to figure out the issue. I struggled for a few weeks trying to figure out what was going on. So glad this worked! Your car looks awesome!Quote from therenoguy on August 11, 2020, 12:58 pmJust came across your post last night, tried it this morning and my car is running right for the first time in 3 weeks!
We have changed distributer, plug wires ....thrown money at it, still ran like shit. Sliced off 1/8" of rubber and car is a running great! Now I can actually look forward to driving it! 67 Gt500 convertible recreation, 351 W with T-5
Thank you Thank you Thank you!
Quote from tony-muscle on August 11, 2020, 2:25 pmJust to clarify, are you seeing the problem as a stuck vacuum/MAP reading or is this also happening when you get varying readings?
Also, can you clarify where is the MAP sensor, or which bolts have to be losen to test?
Tony -
In the logs you will see this as a stuck MAP reading but it may fluctuate a small amount in a single log (like less than 10) or it may show different MAP numbers in each log (so one log would show MAP 49-52 and the next one would show MAP of 66-69). When its working properly mine has a range of like 45-95 in one log it was not even close to that prior to the fix.
So it is actually pretty simple - on the front of the Unit (where it says Fitech) there are four allen head bolts that hold on the ECU, just take those off and the ECU will detach from the throttle body, the gasket is basically in the middle of the ECU near the bottom (closest to the manifold). Just trim the stem (see picture in the other thread) and then reinstall.
Good luck let me know how it works out. If you want me to take a look at a couple logs just post a link to drop box.
Hi all!
Just got my FiTech operational yesterday and system too early in "learning" to say if any issues are from lack of miles or something real. Have experienced a couple of stalls when decelerating with no load (clutch in approaching a red light, for example). If I stab the gas to raise the RPMs, the engine will usually kick up idle to ~800 following this, otherwise it drops to 400-500 and then either recovers or sometimes dies. Have not started digging into data yet but if it turns out to be the gasket trim need described above, how much of the round tip is left after trimming? Would be helpful to provide a measurement instead of "trim off 1/2", as FiTech may modify this at some point and wouldn't want others trimming an already modified part. Thanks!
(1965 corvette, M21 4 speed, 350 ci with modest build, pertronix 3 points replacement)
Welcome! Here's some info from the fitech website:
Decel Fuel Cut Off
When you let off the throttle and deal with your vehicle the EFI will reduce fueling to prevent popping and an over-rich condition that would occur if the fueling continued as it normally would. Depending on the size of your engine, camshaft specs, engine temp, gearing, and several other factors like environmental conditions, you may have either too much or too little fuel cut on deal.
In order to change the amount of fuel it applies, you must go to Go EFI Tuning and then find Fuel Cut Control. Inside this menu, you will see an option called DFCO Return fuel. This number represents the amount of fuel the system will inject when you start to give the vehicle throttle again. If you are having a hesitation when getting back in the throttle then add to the DFCO Return fuel to give the engine more fuel when transitioning back to acceleration. You may also need to adjust your accel pump settings to help with this transition, as well.
Sounds like you may be cutting off too much fuel.
I also have the problem of revs dropping to 300-400 when coming to a stop, sometimes stalling, seem to be worse when I slowly ease to a stop, not when I brake normally, mostly close to home before engine fully warms up, I have a automatic that slipping into neutral makes no difference, have altered DFCO return fuel makes no difference, have checked red gasket, it is like fuel cuts too far or for too long, IAC is good.
Before joining this forum today I had my FiTech 30002 to FOUR shops and 1 professional EFI tuner before I took it off and sent it back to FiTech for WOT stumble and unable to retain programing from day to day. FiTech sent the unit back to me and said the IAC needed to be reset in the ECU. I did multiple resets in the past. I thought OK I will try it as they are the EXPERTS! I put it back on and now am chasing the same Demons I did before... Another words... Back to square one. I joined this forum to find FiTech has a service bulletin on this but yet they didn't perform this fix before sending it back to me. I hope to work with FiTech to get this resolved. I will keep you posted what their response will be. I wish I would have joined this forum $2k ago saving shop and tuner expenses replacing the distributor twice and hours of shop time on the phone with FiTech tech support. I'll post my results soon I hope.
I opened mine up this morning and found that indeed my seal was too long and mashed crooked.
I took it out rubbed it in my fingers and it it returned to the original shape I then cut it reinstalled then tested it out.
It definitely doesn't surge anymore as I'm cruising but I still have a lean tip in all the time, taking off at a light, after coasting can't seam to find the setting for tip in.
Anyone know where the tip in setting is?
Your help would be most appreciated
John
Oh and how the setting works ie: increase value = more or less fuel thanks