Awful lean stumble after coast
Hello and thanks in advance for any help.
Working on tuning this street efi 400 hp system 30003. It has this very annoying stumble when getting back on the throttle after a coast of only a few seconds or more. As long as I am on the throttle cruising and hit it no problem. The thing that really seems to be a problem is the coasting. It is installed on a mild 402 BBC. Frame rail mounted pump.
I have tried lowering the fuel pump pwm on setting to about 1100 and the TPS on to something low like 12%. I have disabled DFCO by raising the enable temp to 300. I have been all over the accel tables. IAC steps are about 4-10 on a warm idle.
I have read many posts here and have tried many of the things suggested. So far nothing seems to help. This thing will go 18-20 AFR and sometimes backfire or die. However if I stay on the throttle the slightest amount no problem. And she runs fine at WOT all the way up to shift RPM.
Yep. In same boat but on longer coasts/ not so frequent as you perhaps. Has only stalled on me a couple of times early on after install. All other driving is just fine...really great in fact. Have tried all the things. I run IAC steps a bit higher at around 9-14 warm idle. I have the 30003 with the Command Center 2 and only on a 258 I6... totally same issue though.
Sorry that I am not much help there but I do understand...ha ha. Keen to solve it and will follow thread + post back if I gain any further insights.
Hi there
Had the same problem
Try increasing Accell Pump 170F
Adjust by 10 at a time
Got rid of most of mine
Update:
So far I have confirmed fuel pressure consistent while driving (ave 43-45 with varying loads). Lot of concerns posted about frame rail mounted pumps. Other than annoying loud operation seems to perform OK.
I also changed the cam setting from 2 to 1. She makes about 14" hg at idle warm. This seems to help some.
Also have changed from premium 93 to mid grade 89. This also seems to help some.
I also leaned/raised the mid range WOT AFR target. This also seems to help some. It is much better, but still does it.
I notice if I increase Accel 170 much the result is a very rich condition immediately after the lean gasp that lasts a long time and has poor performance as well. I tried going negative on this setting but no real help there either. The best so far is about +5 -to +10 at the most.
I am having difficulty getting a data log from hand held to lap top. The laptop is on Win7. Tried to download driver one time and failed. Second time I tried I get some files but none of them logs. One was an instructional guide for the handheld. Others seem to be set up info. But no data logs. Not sure what is wrong on that. Tried searching posts here and on the www but still haven't figured it out.
Have been emailing tech and they have been helpful but as expected, that process is not fast.
Glad to see this string, I have the same problem. Mopar 440, with the sump pump. Started with the frame mounted pump and could NOT stand the noise, considered going back to a carb but decided to throw more money and go deeper down the rabbit hole LOL. General drivability is certainly better than carburator but this lean stumble is the only issue.
I was able to get the K-Line adapter working and connect to the Procal software finally. That really is awfully slow and cumbersome to use. If that is the best it is I am not impressed. If there is a solution for that I am all ears as well.
I suppose we will let this rest for a while. Since fitech is silent (not a word from them for over a week now) and I can't hold this vehicle hostage forever. So as soon as I can get some support from fitech I will try to get this vehicle back to resume the fine tuning process. If a solution is found I will post it.
I changed my Cam setting in the initial set up menu from 3 to 2 and huge improvement!
I did finally get a response from fitech. They believe there is a fuel delivery problem. I replied that I have monitored the available fuel system pressure at the throttle body inlet during multiple events and found no faults with available fuel system pressure. To do this I used a 0-100 psi pressure transducer and graphing scope meter (Vantage Pro). Furthermore the vehicle runs well at WOT all the way to shift RPM as well. With no drop outs or loss of available fuel system pressure at the inlet of the unit. Therefore, I suspect it is possibly a problem inside the unit itself (if it is not a correctable issue in the programming). I asked if they offer a bench test along with needed service and repairs. I also submitted the current cal. Which drives pretty decent except for this lean to rich problem it has upon reapplication of the throttle after decel or coasting. So now we wait........
Did you get any answer back from them? I see lot of guys have this type of issues me including. They just keep saying adjust your IAC, thorttle blades, add accel fuel, do not disable DFCO, check your fuel pressure. Now I have done all that multiple times and I still get that coast to accel hesitation.
Update:
Did recently get a software update from them. Had to get vehicle back. Just got it installed. Many more tuning parameters.
Also found had a DTC stored for "RPM Noise". Will move blue fitech tach wire to MSD grey wire tach output from Ready Run dist instead of Coil -. Then will start over the tuning process.
We also talked about changing vacuum source to distributor vacuum advance from manifold to ported.
Gonna work on it more and report back.