engine stumbles stutters
 

i have a problem. when i try to increase rpm the engine stutters stumbles and has no power. almost like the exhaust is plugged.up. feels like when i melted a cat on my old car and it clogged the exhaust. this car has full RB exhaust no cats. Its a NA 4 port 13b s5 9.7 rotors. street port with itb's, adaptronic 440d universal select. 4 Direct fire IGN-1a coils. 750cc bosch ev14 injectors. Its been 2yrs sense i did the efi swap into my fb. It has been running great. i drive it daily. this problem started month ago. When i try to increase rpm it starts stumbling around 2k rpm air fuel ratio goes lean and has no power.I did a compression test and all 3 faces on both rotors have good compression. i changed the tps sensor, fuel pump( bosch 044),fuel filters were cleaned, checked the crank angle senor wiring. timing. Changed o2 sensor (MTXL). Changed the plug wiires .Changed the sparkplugs(rx8 plugs) i have no fuel or ignition safety cuts. I have throttle off overrun disabled. I checked the wiring on everything. i use wari most of the time. But have tried Eugene. Nothing changes. the IGN-1A are supposed to be bullet proof. i have no way to test the coils with a scope. but i can varify they all work with a timing light. Ive attached my file and log from last run. I just hope its something that i over looked or i have set wrong and not the computer. i dont think the problem is anything mechanical. Any help would be greatly appreciated. thanks in advance.

Looks like a fueling problem from the log. have you checked your fuel pressure? your ecu file shows 750cc primaries and 450cc secondary is that correct? what did you change, if anything, between when it ran good and when the problem started?

Thats what I first thought the problem was. Fuel pressure stays steady at 43psi. It has a brand new Bosch 044 pump. I hooked up the gauge so it popped out the hood some. So I could watch the pressure to see if it dropped at all while driving. Stayed at 43psi. I had the injectors cleaned. Filters cleaned. I think i ruled out any problems with fuel delivery. I used to have the 450cc injectors as primarys but the secondarys would never come on. The select in VE won't kick in the secondarys till the primarys are 98% duty cylce. So I basically run it like I only have two big primarys. No secondarys. Im now looking at the innovate mtxl as my problem. It has a brand new sensor. But has been acting erratic last day or so. Check all the wiring with that.

that wideband sensor isn't going to cause you to stumble like that. data looks good and is following your map pressure which tells me you have a fueling problem. if you have 43psi fuel pressure at the rail even when the problem is happening then it is time to move down the line, something is not providing enough fuel. check your wideband if you want but something is causing a stumble and it looks to be fuel related.

maybe someone else can see something i don't

Ya I hit the gas and it falls flat on it's face. It goes lean 22.9 for a few seconds then just sputters until I let off the gas. Idles fine. The voltage to the injectors looks good. Only thing I haven't looked at fuel wise is in the tank. I made the 3/8 pick up and return in the tank but not much to it. Been in the car couple years now. I have some other injectors that I can try out. This is a fairly simple fuel system. Not much to go wrong. I've been trying to fix this for awhile. Checked all the basics now I'm double checking.

doubtful that it is in the fuel tank or you would see the pressure drop. try the other injectors and see what happens, hell if you know your 450cc secondaries work try those in the primary position. something is causing the fuel to go lean and that is the source of the drivability problem. could be a mechanical problem with the injectors, did the place that cleaned them flow test them afterwards?

​​​​​​. ​ So I changed the injectors to some 550cc seimens daka I had run before. I entered the dead times and all that. I started it up and it was fine at first. Then after maybe a minute. It started doing the same thing. I logged the whole thing and I'm watching the ECU gauge window. Reving it up in my driveway for 10 or 15min. So I can capture the problem on the log. Then it just quit doing it. So I drove it around and it was back to normal. All the power was back ran great. I need to go back and look at log to see if I have a temp setting wrong on something. I also have a video of the ECU gauge window that I recorded the moment it stopped doing it. I did notice that injector #1 was flashing to 0v when I had the problem then stopped doing it when it ran good. I just hope this problem stays away or can figure it out and fix it.

So far so good. Runs like a champ. I think that will be the last time I get injectors from five0motorsports. I got the 550cc from them too. But the Bosch ev14 never really ran that great from the beginning. I was expecting more out of them and I was disappointed with the results. Now I'm starting to believe they were flawed from the start. I was starting to believe that the ECU was bad. So I'm very happy with the outcome. But looking at my logs im over 80% duty cycle at 6500 rpm on these 550cc. What I did before with them was increased the pressure to 60psi increases the flow to 640cc. need to find some new ev14 good ones. Thanks to all that helped.

I really like my injector dynamics injectors. they have good low fuel delivery performance so big injectors can idle nicely and seem very accurate so far.

Been awhile since i last posted. This problem still exists. It goes away for a few weeks or days comes back. I've gone through the whole fuel system. Drain the tank twice because I thought I had a bad tank of gas. Problem went away for a week after I changed injectors and the first time I dropped the tank. Each time would come back. This time it's been down for 2 months. I gone through the whole fuel system. Thought it was something electrical. Like a short so I rewired and made a completely new harness. There were a few things I want to do different anyway. Mostly running the harness through the inside. Instead of over the motor like it was stock. (1985 fb carbed previously) still same problem.. No power. Falls on it's face when u give it gas. Yesterday I tried rewriting a new program from scratch with e440d base map. Wouldn't start. Loaded old program back in with a different ignition timing map. It starts and runs Ike it was brand new. Have power runs great. On the test drive the hesitation starts to come back a little after a 20min drive. As always the logs look good. I load it up in megalog veiwer and notice yellow lines going down the screen. I will try to load the log up later internet connection sucks lately.. Att sucks.
https://cimg8.ibsrv.net/gimg/www.rx7...3859800796.jpg
Screenshot on megalog veiwer. Yellow lines? Nothing checked off in yellow. Doesn't show up in adaptonic log veiwer.

not sure what I am looking at but those signals look real noisy, any chance you have a grounding or EMF issue?