November 8, 200421 yr 127 MPH and it was still pulling on stock boost....let off cuz it was time to exit the Interstate and it reached 6k RPMs. Now...the boost issue... the car run perfectly fine from idle to 6300 on stock boost...start to run out of breath around 6k+ due to cams and small turbo... With turning up the boost, anything more than 10 and the engine just stumbles all over its self with NO POWER past 5200 or so...its like the engine is getting no fuel or spark....but when it boost CREEPs by its self, it likes it just fine.... Ive tried different coils, plugs and so on...timing and such...no luck. Just...nothing. No power, and stumbing and no go...its like its hitting a sporatic rev limiter. Ive never had the 87+ cars do this which is weird. But...the MIDRANGE (3k to 5k) it pulls LIKE MAD. But thats not a useable powerband on atuox course...too much shifting...have to play with about 6 gears...1 hi/lo...2 hi/lo, 3 hi/lo...and sometimes 4 lo. Any suggestions would be great. Stock internals with 87+ turbo cams in 86 GL-10 turbo wagon...spyder intake and XT6 throttle body, WRX TMIC, oil cooler and big thick rad keeps the engine at 180 deg at all times. It also did this mess before the spyder conversion.
November 8, 200421 yr Sounds like fuel starvation. But you say it was like this before the spider intake and XT6 TB, so now my thinking that theres to much air being forced in doesnt hold much now. Might need to find some bigger injectors or bigger fuel pump maybe?
November 8, 200421 yr Author Sounds like fuel starvation. But you say it was like this before the spider intake and XT6 TB, so now my thinking that theres to much air being forced in doesnt hold much now. Might need to find some bigger injectors or bigger fuel pump maybe? Whats weird is that on the 87+ cars it doent do that mess...and im running the same injectors as them...and the exh is just spitting out a fuel cloud when its doing this mess....too much fuel? maybe I should play with the flapper door on the air flow meter...
November 8, 200421 yr Maybe the XT6 TB TPS is acting up. Is it wired the same as the spider? Picking your brain a little, might be doing the same upgrade.
November 8, 200421 yr Author spyder and 87+ and XT6 have 4 wires....and all the 86 tps stuff has 3 wires. So...its not even hooked up really. But Like I said...it did this BEFORE i switched over TB's and stuff...when the intake was the stock 86 unit.
November 8, 200421 yr well if you don't have the tps hooked up then it will cause problems or even if its hooked up wrong the tps all work the same just differnt wiring conection but they both have teh tps part and the idle switch in the unit does it feel like it bogs down and then recovers a bit if you let off?
November 8, 200421 yr Author No. But when it does its thing in hi boost, and I shift qucikly and get on it...it still does it at lower RPMs...i have to let off again for a second or two then it goes again. Did this BEFORE XT6/SPyder conversion as well.
May 1, 200520 yr Your hitting Fuel Cut due to Overboosting. The ECM is programmed to cut fuel over stock boost levels.
May 1, 200520 yr Your hitting Fuel Cut due to Overboosting. The ECM is programmed to cut fuel over stock boost levels. Actually, being an 86 model, ovrboost fuel cut can be and probably has been disable. Aditioanlly, I think that car has since been blown up, ressuected and replaced with an RX:-p
May 1, 200520 yr With turning up the boost, anything more than 10 and the engine just stumbles all over its self with NO POWER past 5200 or so...its like the engine is getting no fuel or spark....but when it boost CREEPs by its self, it likes it just fine.... Maybe the power drop off thingamajigga after 5500rpm rears it's ugly head again with higher boost. I don't know why it does it stock but whatever causes it to do it stock may be doing it again at higher boost levels. :-\
May 2, 200520 yr Author Your hitting Fuel Cut due to Overboosting. The ECM is programmed to cut fuel over stock boost levels. WRONG. 1985-1986 fuel cut can be unplugged and perminatly disabled. 1987 + MAF-Hotwire cannot be unplugged....its built in with the voltage input from the MAF. the problem was that the Vane air flow meter was NOT calibrated correctly with high boost. After tweaking it this problem went away. It was NOT getting enough fuel up high and running SUPER-ULTRA lean....hince the stumble and short engine life after that point. This porblem does NOT exist on the 87+ MAF-Hotwire systems, but you do hit fuel cut after 10 seconds of 9 PSI+.
May 2, 200520 yr How did you tweak it? On a rolling road or by trial and error? I ask because my same era RX (with mods) also does this sometimes at high revs (ditto fuel cut disabled) WRONG. the problem was that the Vane air flow meter was NOT calibrated correctly with high boost. After tweaking it this problem went away. It was NOT getting enough fuel up high and running SUPER-ULTRA lean....hince the stumble and short engine life after that point.
May 2, 200520 yr Author What I did was pop the cover off the air flow meter (AFM from now on) and adjsut the spring tension for the flapper door in there....that way it in essence made the car run a little bit richer than normal...and gave it more fuel up tigh. However...its still not enough fuel with stock injectors and engine management for it to last under long periods of high boost.
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