rolfs_7

cars an 86 NA with an s5 NA swap. runing s5 ecu and ect. heres the deal. under load or not at WOT it will buck and backfire and pop. if i rev slowly its fine no big deal. fuel pump seems to be fine, new fuel filter, all injectors are fine, fuel system is building and holding pressure, and the secondaries will come on (when the pressure sensor is unplugged). i did notice tho wondering if it was the TPS possibly (TPS is set btw) that after i unplugged the TPS that there was no real diff in the way it acted? MOP is plugged in but not on the engine. has all emissions removed also. checked and fixed vac leaks. timing is good.


heres a vid.

http://www.youtube.com/watch?v=F63G2yOLfUA

from :02 till :04 i slowly rev it up then at :08 till :19 i try to go WOT and thats what it does

rolfs_7

also since its got an S5 swap in it i cant pull the engine codes cuz im not exactly sure what pins at the ECU are the pins i need to hook up.

iceblue

Did you bypass the injector resistor pack or use the S4 injectors? Are you using the S4 harness?

rolfs_7

no i installed the s5 harness

iceblue

Then you still need to bypass the injector resistor pack behind the driver headlight

rolfs_7

no...s5 engine harness, ecu, sensors, injectors, and engine. resistor pack is removed.

iceblue

I came back bc I was in the shower thinking about this and you saying you put in the S5 harness and the resistor pack is part of the emissions harness so u would of already ditched it.

How far will the motor Rev in RPM? Listening to it the motor sounds like it could very well be electrical. Have you bothered to check the ground at the ECU? the S5 has another ground wire at the ECU box. I have seen them do this and this ground be the culprit.

rolfs_7

i have a ground directly to the ECU but not to any pins on the ecu? is that what your saying. but my other ? is about the TPS. it acted the same with the TPS unplugged. that normal for S5?

rolfs_7

o ya and it doesnt really matter what rpm i dont think its just WOT period. slowly reving its ok but not matter where ur at. WOT it does that.

HAILERS

Grounding the ECU chassis does....................nothing useful at all. You can set a ECU on a piece of foam and drive your heart out to 150mph. It's the internal grounds of the ECU that have to be grounded.

I'm kinda big on doing that on a series four, but by the time they came out with the series five that *problem* should have been taken care of. So I'd recommend finding the grounds for the ECU at their end point. As on the engine itself and make sure they are clean and bolted down.

There is one ECU ground that is near the ECU on a series five, but it's function if memory serves is not worth mentioning. In fact I forget what it's for. See series five FSM for the ECU ground termination points.

EDIT: That gnd near the ECU is for........the 02 sensor on a series five. https://www.rx7club.com/showthread.p...ght=ECU+GROUND