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Okay, first of all I picked up my car tonight after 10 months of...whatever. It starts up great, runs great, EXCEPT when I get on the gas more than about 1/4 throttle.

The boost builds to 8lbs fine, but the A/F ratio seems to be going whacky. It started out bouncing from about 14.5 to 17 (pegged), which was worrysome. Then about halfway home (~15 miles) it started going from 14.5 to ~12...better. But, it would stay around 14.5 if I was just cruising - as soon as I'd apply "slight" throttle it would go to 12 and start pulling pretty nicely. Then, it would bog down and drop back to 14.5 once I got around the 1/4 throttle point.

It seemed to be getting a little better the further I drove, and when I finally pulled into my garage I noticed the needle was at ~12, solid. No fluctuation at all. Naturally, this was by the time I had already pulled in and I didn't feel like going back out at 2am.

So, after this long prologue, does the stock ECU need time to adjust to a new setup? You can see my mods in my sig.

I'll be out first thing tomorrow driving it around - given the new motor only has ~30 miles on it I'm hoping things continue to improve.

I will say it is fast as f**k compared to the Escort I've been driving for the past 10 months, even without hitting the boost!!!!

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I forgot - the car will accellerate smoothly up to 4500 rpm as long as I don't go to much on the throttle. Once I hit EXACTLY 4500 it falls on its face, regardless of throttle. Again, the A/F gauge shows it's leaning out.

Any feedback would be mucho appreciated - I'll keep ya posted how Sunday's drive goes

ps: The boost controller is currently turned OFF for the break-in period. Just an FYI, if it helps.

rynberg

First of all, those A/F readings are useless if you are using the stock O2 sensor. The variations you are seeing are probably due to changes in the readings as the sensor heats up.

Secondly, you are having some serious problems with your car. Take it back to the shop who installed the engine.

Thirdly, it's a new engine. Why are you trying to exceed 4500 rpm?

EDIT: Actually, its sounds like your car is in "limp home" mode. Reset the ecu by disconnecting the neg batt cable and pressing on the brake pedal for 30 seconds. Also, make sure the MAP sensor hose is connected.

SilverRX7

Correct me if Im wrong, but I dont think the ECU has learning capability outside of 2 engine cycles...

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I wasn't trying to go past 4500 rpm by flooring it - accellerating smoothly and slowly. we had had problems with it bogging in neutral then switched some stuff and that went away, but we needed to see what it would do under a load. anyway, i only did that twice.

resettting the thing never even crossed my mind. i'll go try that now and see what happens.

if that doesn't do the trick, though...?????

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btw, thanks for the feedback....regarding the o2 sensor i can't remember if we replaced it with the 3 wire or not - i'll have to double check.

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Okay, I've been driving it around for a few hours today, here's what I noticed:

As soon as I hit 4 lbs of boost it cuts off and falls on its face. I can accellerate fine until that point. It starts up perfectly, pulls nice and strong under no boost.

I have my manual boost controller hooked up but turned off right now while I'm breaking it in; could that possibly have something to do with it?

360spinner

Did anyone find the answer to the problem at hand cause i am having the same problem except mine is stalling when i come to a stop but all the other symptoms are present.. Pm me please if anyone has any positive feed back

clayne

Once again, fuel pressure regulator vacuum line hooked up properly?

Jeff RX7

Hi there,

Have is the breakdown, the source of the problem. I am French and owner of a FD and I have had exactly the same problem for 6 months on a new engine. I cannot any more what make. I reset ECU many times but nothing better. I can't accelerate over 3 PSI boost pressure without cut off !!!! My boost sensor is new. My car is stock, I just installed a streetlight flywheel and a complete HKS exhaust. After 4000 - 4500 RPM = no problem : I have full boost ????

soru81

One slightly off topic question:
Let's suppose at point of falling on the face, wideband shows very lean condition. How do you explain this?

1.) No fuel -> lean condition, no combustion and no power.

2.) Because oxygen sensor doesn't directly meter the A/F mixture, but indirectly meters it with help of chemical reactions, I wonder whether this really means no fuel. I mean, what does the wideband show, if there's no spark, just fuel and no combustion -> Does it show lean too?