Stalling when coasting from highway speeds or abrupt close of throttle.
Hello all,
Want to say thank you in advance for any/all information. I have been doing a bunch of reading and trying to adjust settings based on my reading, but still not getting the results I want. To start, I have two Jeep CJ-7's with Chevy 350's in them. Mine is a stock 350/350 with the Go EFI and a manual transmission. I have this system running very well and have not experienced any bogging or stalling issues. My second CJ is a 375/350, slightly larger cam but has a 700r4 behind it. Back history on this system is that the ECU went bad and FiTech replaced it during a RMA. When I got the unit back, I noticed there was a slight popping noise when opening the throttle as the blades were slightly sticking. Comes to find out, the butterfly rod nut was loose so I tightened it and the blades no longer stick. Anyways..I used the updated procedure to set the IAC steps for this system (adjusting front and back) and I can get the system to idle pretty well. It does bounce around some, but it is close to the target. The system with the manual I only did the front it is smooth.
My issue is when I have an extended coast with hardly any throttle input. Sometimes when I get back on the throttle it stumbles and other times it just completely dies even if I am doing 35 mpg. Last night, while I was trying to tune it, I was blipping the throttle and it was running well until the last manipulation which went closer to WOT and as soon as I released the throttle, it came down in RPM some and just stalled. I have tried both the CAM 1 and CAM 2 setting and the CAM 2 setting seems to start and run better. Sadly I do not have the CAM specs as it was replaced by my father before I got the Jeep from him and he did not have the specs. The FiTech sits on top of an Edelbrock performer airgap intake and GM HEI ignition. I am not using timing control.
My latest reading has been on the MAP sensor and I am considering opening it up...but have not gotten there yet. If anyone has any suggestions or tuning specs for a similar setup I would be happy to hear them.
A few things. What model of FiTech do you have? Inline fuel pump or intank fuel pump? In regards to your going back to the peddle after coasting and it stumbles or dies, this is related to DFCO. I and alot of others disable it as it is difficult to get set right and I dont know why FiTech cant get it right out of the box. To disable it, go to GO-EFI Tuning in the handheld and select FUEL CUT CONTROL. In the Fuel Cut Control section change Dfco Enable Temp to 300, so that Dfco never comes into play. That should fix that issue. You will waist a bit more gas, but it is better than stalling. Also you should check your MAP sensor seal to make sure it is not deformed and should be trimmed. You need to remove the from cover where the ECU is to inspect it. There is a section in this form which explains about the MAP sensor seal. For a 350 Cu inch motor you should be using CAM 2 or 3 settings. You can change the value while the car is running to see what works better with the engine. But most of all watch Fitech video's on their youtube channel as it has valuable info there. There is a new video every Tuesday and I learned alot from the video's. For me personally, if my FiTech ever fails, I will install the Edelbrock Pro-Flo 4 system instead or convert to electric as electric will be the future way of powering up our classics. The problem with Fitech and Holly TBI systems is the fact they are made in China and the electronics in the ECU are poor quality and not built to stand the heat and vibration as there are alot of users having ECU's go BAD. They really should have the ECU's externally mounted and made in the USA with quality components, even if it was to increase the retail cost $200 to $300, it would be well worth it.
Thank you for the reply. I have been checking on the on Tech Tuesdays and have also picked up some new knowledge from them. I think some of the confusion is that there is so much "old" information out there that has been surpassed people are not sure what to do. Most of the FiTech videos I saw about setting IAC never told you to put the car into Idle mode before doing it, I got that info via email with FiTech and I think I have only seen on video showing that. Thank you for the Cam setting suggestion. I had this one already set at a 2, since it was a mild 350, but after reviewing my almost stock 350 in my other jeep it was set at a 2 and I know it is less powerful. I set it to a 1, and the thing ran like crap. I will try CAM 3 to see if that makes any improvement. Fitech also got back to me with some suggestions which I implemented and so far are positive. I need to keep driving it though and add some miles. I will also play with the DFCO if I keep noticing the issue. I check the MAP readings with the car running and I did not see any stuck values there, so that MAP sensor may be alright (for now) but will keep an eye on it. I just started having the low temp sensor reading on one unit so I guess I will replace that temp sensor.
Fitech suggestions: Main Menu-FiTech Tuning-Accel Pump-Fast Accel 170 Bump up 10-Accel 170
Bump up 10