BPT Ignition Problem

[carkrazed2005]

I've been tryin to figure out a gremlin that has plagued my car for about a month now. The main problem is that for some reason, my base timing is messed up. If I set it at 12 deg advance, its not right, its WAAAY retarded. I have found that it runs right at 32 degs advance. It runs right at idle and at cruise, but when it starts to boost, it starts to pull like crazy then falls on its face, boost gauge drops to zero and wideband pegs to rich. It seems as though the computer is cutting spark. Some help with this would be great, i'm at my witts end.

My setup:

BP05
P&P Head
Stainless Valves
.50-.63, 57 trim Master Power T3/T4
1 3/4" ramhorn
Mark 2 Deltagate
Turbonetics MBC set at 15
3" mandrel downpipe
3" mandrel exhaust
24x11x3 Greddy Intercooler
2.5" mandrel charge pipes
Greddy RS BOV
GTX ECU
GTX Injectors
GTX Intake Manny
AEM WideBand
AEM Water/Meth Injection

Things i've tried to fix it.

new engine temp sensor
swapped tps
swapped air meter (gt)

new plugs, wires, cap and rotor
plugs gapped .028
swapped distributor
belt timing is right on
No vac leaks
No charge pipe leaks
fuel pressure is good

I've searched on here and found that there are a couple people who have had the same timing problem but nobody has posted what the fix was. Thanks in advance for any suggesstions.

[FE3-323]

open your spark plug gap & sell off your GTX ECU, your probably hitting the ecu cut.

[carkrazed2005]

open your spark plug gap & sell off your GTX ECU, your probably hitting the ecu cut.

Really? You think I should open them up.

The boost cut, cuts fuel though right,when it does it, the wideband pegs to rich. Which, boost goes to zero, so it would have to be spark. Maybe I'm not getting a hot enough spark to detonate. I'm geussing thats why you say to open the gap up.

Also, I thought you wouldn't get boost cut without the gtx airmeter.

I'll be selling the gtx ecu off as soon as I save for a MS.

Thanks for the idea.

[jay]

If you don't get half-inch long sparks from the plugs to the valve cover when you crank it over, replace the coil with something that'll not blow out under boost.

[therieldeal]

it sounds like your spark is blowing out. opening the plug gap is going to make it worse.

.028 should be fine unless your coil is weak as jay mentioned

[FE3-323]

changing to a RX7 afm & 460cc rx7 injectors allows you to run higher psi then normal, you do have to adjust the spring tension tho.

I would figure the ecu to cut spark not fuel. theres a chance to run lean & grenade if its fuel cut.

[therieldeal]

stock ecu's cut fuel. spark cut limits (revlimiters or otherwise) will kill catalytic converters by soaking them with unburnt fuel.

[Mazda_Powered]

i thought the gtx VAFs were the cause of hiting fuel/boost cut? i've heard of ppl replacing them with the rx-7 VAFs and tighening the spring to solve this issue.

JACK.

[carkrazed2005]

Today I opened my gap to .035, same thing. I then closed them to .025. Same thing. I determined that this is not the boost cut because I turned my boost controller all the way down to 10psi and it still does it. I did run these plugs for a little bit while the ignition was way retarded and running incredibly rich, so i'm gonna pick up some new plugs tomorrow.

Anybody have a pic of the wiring on a 4 wire tps, I didn't have a connector when I put mine on so I just wired it up off a diagram. I'd just like to make sure I have it wired right. I searched for this but could not find how to wire it without already having the pigtail from an auto.

[FazdaBoy4ever]

10 psi doesnt mean anything... running 10psi in a MUCH larger turbo than a vj20 you could still easily be flowing enough air to trip your cut.

[carkrazed2005]

10 psi doesnt mean anything... running 10psi in a MUCH larger turbo than a vj20 you could still easily be flowing enough air to trip your cut.

Yes, understood, more volume at same psi, but I ran this same turbo at 10 psi before with no problems. Guess I should have mentioned that.

[FE3-323]

you need to change a pin or 2 @ the ECU end & loop one feed wire into the VAF from the TPS sensor

[carkrazed2005]

you need to change a pin or 2 @ the ECU end & loop one feed wire into the VAF from the TPS sensor

Yeah, i changed the pin at the ecu a long time ago. I just need the find a pic of the wiring at the sensor since i do not have the factory plug. I can't find it anywhere though. I hope to be able to mess with my car a little this week. I havn't been able to because I have been doing a V8 swap in my ranger but I just got that done.

[nos92mx3]

what year is your bp?

[carkrazed2005]

what year is your bp?

1991 EGT

I messed with it a little bit today and I think I might have a weak coil and spark is being blown out. I think I read that others had this problem. Didn't you have this problem therieldeal? What coil did you use? It confuses me because I would think that if it was blowing spark out, it would misfire not just fall flat on its face. Maybe its just bad enough that it blows out all spark whatsoever. Whattya think? I'm so close to saying F it and order a megasquirt.