Fi-Tech Go-Street 30003 400hp fitted to 2.8L Ford Cologne V6.
Hi, I am new to Fi-Tech. I have recently fitted the Go-Street 400hp system to my V6 Ford Cologne engine, fitted in a 1979 Ford Cortina (I am in England). It works pretty good but after trying for a week now to eradicate an acceleration problem, (and getting no replies from FiTech themselves), I wonder whether anybody on here might have an idea. All the AFR's are good, engine nice and smooth, and the hard accel is very good, BUT, if I am cruising at 30 or 40mph (MAP of 45 to 50 and with TPS at about 6) and try and gradually accelerate, for a fraction of a second it goes lean and there is a hesitation. I have tried adding 20 or even 50 to ACCEL PUMP 170F, but made no difference. I have also increased dTPS Acc GAIN from the default 109 up to 150. This has helped slightly but has not cured the problem. I was suspicious about my dizzy vac. I was connected to the timed port on the "carb" and was concerned the hesitation was due to the vac advance not starting early enough. When I looked in the throat, the timed port drilling was well above my throttle blade !. I checked and found the TPS would be at 9 before uncovering the port !. On my Holley carb, the port is uncovered almost as soon as the throttle is moved. So as a test I connected the dizzy vac to manifold vac instead. This has slightly helped the problem. The vac advance is there when needed and not delayed. The problem is still there however, and it is as though the fuel injection is not fast enough to keep up with demand. It goes lean before it can add fuel. Sorry to go on, but I hope somebody can help. Thanks. I hope this post works, I have never been on a Forum before !.
Uploaded files:- You need to login to have access to uploads.
How did you set up your fuel system? Wonder if there is a fuel supply delay.
Hello there. I have set up the tank with an in tank Walbro 255L/hr fuel pump and a return line. I don't think there is a fuel supply delay because when the throttle is given hard rapid accel, there is no delay or leanness there. That works very well, if anything it is a bit rich but I will sort that out later. This fault occurs after cruising and then just slightly accelerating. There is a hesitation, it goes lean, and then picks up. If I adjust the Accel 170F parameter up (richer), the hesitation still occurs, but immediately afterwards the AFR goes richer (corresponding to the richer parameter). The MAP and TPS sensors are showing the throttle increase immediately, but it is as though the system cannot keep up on this type of gradual increase. I have another fault which may be connected. When throttling off into a bend and then re-applying the throttle afterwards, there is a similar (bad) hesitation. I have upped the Dfco Return Fuel from 68% to 150 and 250% but that made no difference to the hesitation, just made it very rich immediately afterwards !. I have also tried increasing the Dry Ring Fill and Max drpm drop rate, and made no difference. Unfortunately this EFI unit does not come with any datalogging software. Apparently I can add a folder in the handheld to get me the data, but I will have to view it with something. I do have Logworks 3 from a previous MegaSquirt project. Will the data view in that ok ?. Again many thanks for the assistance.
Thanks for the more detailed reply. Try disabling the DFCO. Manual trans vehicles and road racing vehicles run into this issue. You can disable by increasing the enable temp to its max value.
Let me know....
DFCO is disabled and had no effect. Here are some Log charts. As you can see the hard accel and fairly vigorous accel are ok, albeit a bit rich. But after cruising or gradual throttle off, and then slowly reapplying the throttle, the MAP and TPS are shown increasing but the Fuel does not keep up or ignores it, and I get a lean spike. The charts were recorded with AccelPump170F at 80, AccelDelay170F at 70 and dTPS Acc Gain at 250, all big figures for this small engine. I am starting to wonder if the Accel Pump parameters do not work on very low TPS or MAP increases, and only come in at higher figures. I have probably been increasing parameters that are only valid at fairly brisk accelerations. What do you think ?
Uploaded files:- You need to login to have access to uploads.
Accel works on light throttle changes. Fast Accel works on hard throttle changes.
I'm trying to remember the area, but there is an area where you can decrease the correction and decrease the sensitivity. I think what you are experiencing is an extreme correction to the rich spikes. Causing a lean spike. These things were programmed around the Chevy 350 and are biased to the safe side. The target demographic is the beginner, so they designed for safe before perfect tune....
I have informed FiTech of this problem and sent them some logs. When (If) I get a reply I will post their recommendations.
This is what I see with your graphs. You are pulsing the throttle very quickly. When the settings are perfect the AFR will be lacking in trim while throttling so quickly. Record a log with more time between throttle pulses. Let's lean into this issue, jump in....
Post log here using Dropbox. Instructions: Save a copy of datalog to Dropbox, select three DOT icon at end of file discription, select share, select copy link, past link to new reply on this thread.
I have had a reply from FiTech about this problem. Here is their reply,
"The log shows that you are increasing fuel a lot during throttle input. The injector pulse width doubles in time during the throttle hit. It appears that you have so much fuel being injected that the engine misfires. This misfire would register lean on the oxygen sensor. You can see after the initial lean spike the AFR plummets to dead rich."
I have assumed they are referring to Accel Pump, so I have reduced it to -20 on both 65F and 170F. It does appear better when driving but I will do a log of it next.
I am currently also really struggling with my idle. It is just not smooth enough. I have a basically stock cam, and when it was on the carb it was pretty smooth. I have the idle AFR at 13.60, but have tried lower and higher AFR's but no better. The engine also nearly stops when I throttle off quickly to come to a halt, and just manages to save itself at the last second. I have got about 9 steps on the IAC at warm idle and TPS at zero. I have tried increasing the "loop rate up" and "loop rate down". That did not really help the nearly stopping and also made the engine over rev afterwards to compensate. I will put a log on of this problem later as well.
By the way, does anybody know what "Decel MAP Control" and "Decel MAP base" are ?. They are in the Idle Control section.
Thanks.