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L20et Sluggish Off Boost

machg

By machg,
in Classic & Vintage (1950's-1980's)

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machg Enthusiast

machg

Posted
Posted

Guys,

My L20et is not happy off boost. When cruising on partial throttle, it is very sluggish when I give it a little more throttle. Once full boost is reached it goes fine. Also when cruising, it will some times stutter for a short period. It never breaks down or stops the car, but it does seem to be getting worse. I have changed leads, so I don't think they are the problem. I suspect it could be something to do with the throttle position sensor or oxygen sensor. Does the engine run closed loop operation at cruise and open loop at wide open throttle? Any ideas what could be going on? Its standard apart from RB20DET turbo and small front mount intercooler.

Cheers,

machg

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blind_elk Grand Master

blind_elk

Posted
Posted

It's only got 7.5 C/R!

Engine only runs closed loop under cruise conditions. As soon as you start moving the throttle off cruise, the ECU should start ignoring the O2 sensor signals.

Is the distributor in A-1 condition? Does the vacuum advance work properly?

stagefumer11 Rising Star

stagefumer11

Posted
Posted
It's only got 7.5 C/R!

Engine only runs closed loop under cruise conditions. As soon as you start moving the throttle off cruise, the ECU should start ignoring the O2 sensor signals.

Is the distributor in A-1 condition? Does the vacuum advance work properly?

7:3.1 to be on the point. Now mine has quite a bit down low. i can drive it happly off boost and not hold anyone up. As i said before. advance the timing to 20btc or 22. The o2 sensor seems to bog my car down alot, and its a brand new sensor. so i dont use it apart for running my A/f guage.

The l20et does get anough fuel to be able to advance the timing, factory seting is 10btc, which is poor. Also the l20et injection system doesnt use vacume advance/retard. Its all electronic optical sensors

stagefumer11 Rising Star

stagefumer11

Posted
Posted
Guys,

My L20et is not happy off boost. When cruising on partial throttle, it is very sluggish when I give it a little more throttle. Once full boost is reached it goes fine. Also when cruising, it will some times stutter for a short period. It never breaks down or stops the car, but it does seem to be getting worse. I have changed leads, so I don't think they are the problem. I suspect it could be something to do with the throttle position sensor or oxygen sensor. Does the engine run closed loop operation at cruise and open loop at wide open throttle? Any ideas what could be going on? Its standard apart from RB20DET turbo and small front mount intercooler. 

Cheers,

machg

YOu state boggin down ect. id also cleen all your ecu plugs and component sensors. I also had similar problems when my TPS was fu<ked.

Crack open your afm and cleen the slider and tighten the afm 3 teath.

george.bryant Rising Star

george.bryant

Posted
Posted
Cheers,

I'll try checking and cleaning some more.

machg

I advanced my timing to 20 a few days ago, motor stalled when gas was just tapped and was very very sluggish off the mark compared to usual. I've put it down to 16 and all seems to be better now.

DO you reckon the O2 sensor should be unplugged? I still need to clean all of my ECU components aswell (havnt done it since i got the car). I played with the screw on the AFM a while ago. How do I know when its set to a good position? I assume i need a Air/Fuel Ratio Gauge or a engine analyzer?

stagefumer11 Rising Star

stagefumer11

Posted
Posted

trying the o2 sensor is a test. i find my car is dog as slow and boggy with it pluged in. Cold start is horrid also... Without it. Ive gained heaps of torque and its smooth as from low down right to redline.

The screew on the afm is only the idle air/fuel mixture. Pretty much lets a small about bypass the afm so you can tune your idle. It doesnt do anything to your normal running rpm a/f

stagefumer11 Rising Star

stagefumer11

Posted
Posted
Haven't had a chance to clean/play yet. Will the Skyline ping if I advance the timing? (I'm in Tassie and we only get shit for fuel down here {95 RON})

machg

i dobut it will ping. Ive neaver heard mine ping. Just do go to hard out on advance and you will be fine.

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