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Discussion Starter · #1 ·
Ok
So I've got an 89 amigo, 5 speed, with a 4ze1
When its cold, the truck will not idle without throttle, and at times you can smell unburnt gas as if its running rich. Once it reaches operating temperature, it runs decent, but it will occasionally surge while accelerating, it idles at about 500 rpmwhich is lower than what it used too, this all started about 2 weeks ago out wheeling, I have replaced the fuel pump, fuel filter, and fuel lines running from the pump and fuel filter.
The valves were last set probably about 4000 miles ago last summer when I replaced two new ones.
The reason for the fuel filter and fuel pump is I checked the fuel pressure when this all started, it was fine at idle, about 40, but under throttle it decreased to about 35. I haven't checked it since the new pump and filter, but I'm assuming its the same since its got the same symptoms, on the test drive today I was running 55 mph and everything felt fine, but the check engine light came on for about 10 seconds and then went out.

would a bad o2 sensor cause this?
Fuel Pressure regulator?
Does anybody have any other ideas?
 

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bad coolant temp sensor possibly.
 

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The 4ZE1 in my 1990 Trooper had similar issues.

For the surge, it turned out to be the O2 sensor. I replaced it and the surge was gone.
 

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Discussion Starter · #4 ·
To be exact, it does start up at cold, its no big deal to get it started
but it starts, idle sits where it should for about 1/2 a second, and then drops and drops until it dies
I like Mark B N.V's ideas since he had to deal with this, I just started thinking about the O2 today, last summer I swapped in a XS gauge cluster, and hte o2 light came on with that cluster, but went out over time,the bulb isn't burned out, because when you turn the ignition it comes on with all the other lights.
Stusvnd, a coolant temp sensor malfunction had occured to me, but I think I'll try mark's ideas first
so you guys don't think it could be the fuel pressure regulator?
 

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+1 for Aux Air Regulator. That thing is suppose to be open when cold & over the space of about 5min slowly close as the engine (& its internal heater) comes to temp. Some good carb cleaner or penetrating lube should help if its just gummed up with blow-by gooy buildup.

~psguardian
 

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Alternator!!!
 

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HEMIII said:
Alternator!!!
It's true the alternator does power the fuel pump and can cause these symptoms as well. The bad cold start thing and the loss of pressure could be two different problems.
 

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Sorry I'm a noob what's the AAR?
 

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HEMIII said:
Sorry I'm a noob what's the AAR?
AAR = Aux Air Regulator - similar to the IAC on the V6 engines.
 

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Where'd you find new one?
 

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AAR ... FTW!
 
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