95RedM

Hey guys,

I'm having a bit of an issue here that I wanted some feedback on. 94 M-Edition with VVT swapped, built engine running 20psi on e85, 350whp. Currently the car is breaking up in boost and when I look at the logs there are 2 things that stand out to me.
1) The RPM spikes/drops when the breakup happens. Causing a rapid change in timing and fueling.
2) My voltage is kinda all over the place on some of the pulls, from 13.1-13.8, going up and down randomly during the pull. I've never noticed this before, and the car still breaks up in pulls where voltage is consistent.

I've checked the wiring and the connector on my crank sensor, the spark plug gap is the same that its always been and never had an issue with it. I've cleaned all connectors, used dielectric on all the contacts. My next thought is to change coil pack, I tried 8.5mm Magnecor wires and it didn't change anything. I've verified timing with a timing light

Also, it doesn't break up like that in 4th or 5th gear. I hit 20psi at about 4000rpm and it will hold steady, no breakup, no apparent issue in 4th or 5th gear. Only happens in 1-3rd gear. And occasionally when this happens the car will go into almost a limp mode where the AFRs are all over the place, and the car is like jerky and bogging and has no power and it almost dies and then it will just clear up suddenly and drive normal. I really have no idea what the hell is going on. Im on a speeyefi, not a megasquirt. Same tuning software, same datalog software. I will post some datalogs here in a little while

95RedM

Here is a pic of the event. Its inconsistent, it doesnt always happen at the same RPM or MAP. But it always happens in 2nd and 3rd gear during a WOT pull. This was like hitting a brick wall. Very dangerous for the engine. Any help is appreciated. This happened out of nowhere and its getting worse and worse

rwyatt365

I had a similar problem after I installed a new turbo. I went through a number of problem scenarios (problems with the tune, coils, wastegate, intake/exhaust leaks, etc...). Finally I changed the plugs - they were NGK BKR7E's, not new but seemingly in good shape - and voila! No more breakup. I don't know if one or more of the old plugs had an internal fault (and, frankly, I don't care) but the car runs like a champ with the new plugs.

This may not solve your problem, but it's a cheap experiment.

Newaza

Hey 95redm
I am using a speefuino setup now as well. specifically the universal fishdog from speeyefi due to the 4 bar map sensor, which I need, and cheap price. I assume you are on their pnp? Couple things you can check if it turns out to not be coils, plugs, crank or cam angle issues. First is do you still have the capacitor in the wiring harness for the coils? May want to add one if you dont. I run one capacitor on each stock coil. Also check connectors, all grounds and for breaks in any wires. Breaks in wires can be a real pita due to their causing intermittent issues. On the connectors in older wire harnesses I usually take a pair of needle nose pliers and give the male blades in the connectors a slight twist to help insure a good connection. Also You may want to verify the grounding for the ecu and the coils. If the coils are grounded to the block the ecu should be grounded to the block as well. If the coils are grounded to the block and if the ecu is grounded to the battery there could be an issue with triggering the coils at very high injector duty cycle.. Did you recently make changes when this issue popped up? Such as adding more boost, rpm or fueling causing higher injector duty than you were running prior?