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1980 GL Wagon EA71 1600 Cylinder misfire..


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Seems to be Cylinder 1

 

Went to smog. Guy said that it has a slight misfire at idle showing 2000ppm on the HC. At 2500RPM it is clean as a whistle. 4ppms. It is not lean either. Swapped plugs, wires. Found some heavy corrosion on distributor cap on the number one button. cleaned. Filters all clean. Great spark.

135 PSI Compression (kinda low? but same as others. ) and 80 psi running. Seems to run good until it warms up. Then kicks down and starts misfiring slightly. THis causes the Idle to jump to 1100 rpm and stumble slightly..

No vacuum leaks. Checked valve clearance. #1 and 2 needed adjusting on both intake and exhaust. I did this with the engine kinda warm. seemed to run for a couple minutes fine, then started missing again.

 

157K on motor..

 

It will not drive past 55-60MPH. Up hills it will slow to 35-45-50. Compression numbers tell me different.. kinda.. But I think it is time for a rebuild. oil pressure on my gauge fluctuates and will drop to 15 psi at idle , but at 2500RPM it will spike up past the 57PSI suggestion in the book. seems okay.

 

Just wanted to get some opinions before I pulled the head and inspected.

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Checked for that. Nothing. I do have a vacuum hose disconnected @ the blower motor area inside under the glove box. It has a 1 way check valve, but I can not find a port to attach. There are 2 vacuum lines there one is plugged in properly..

 

I think i need to run a vacuum test. I'll throw the numbers up when I get them.

 

EGR is in the center rear of the motor. below to the starter (1st gen)

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Update. Found 19 inches @ 4000 feet with a 1/2" drop when it misfires. when I snap the throttle, I get a drop-then spike to around 25-26 then back to 19

 

Found what appeared to be a couple very small vacuum leaks. repaired. No change. Also found that if I spray some brake clean right behind the carb @ the gasket just above the mounting gasket, the engine wants to stall..

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No, the temp is great. Fan comes on, keeps everything nice and in the low norml temps. Drives fine too (just slow) has no hesitation or jerking. The Very slight misfire goes away at 2500RPM every time. Smog tech said machine reads that it is not running lean. Catalytic converter rattles a bit on decel.

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Okay, so I rebuilt the carb. Fired it back up and..... Still there.. Installed OEM NGK plugs and wires. Also installed Coolant temp switch also poured some fuel treatment down the carb. Started and ran for a few minutes @ 2000RPM. dropped to 900 started putting/slight misfiring again, took it for a drive down the highway got back idle is 900 and now seems fine.. Gonna take it to smog Tuesday if it keeps up.. :grin:

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Went to town (50 miles)... By the time I got there, the car was completely warmed up and it started missing again.. I pulled the heads and found just what I suspected.. Cracks on 3 of 4 cylinders right between the valves.. #1 being the worst.

 

I have two EA81 Engines with heads. They look the same.. Will they work? Anyone do this swap before? I know that Many of the heads between the WRX and STI years are interchangeable..

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Found a thread on these forums from some subie junk yards. In a very detailed post, I found that "they say" that the EA71 and EA81 heads will interchange And "Vise Versa".

 

Oh well.. I'm at the point where I have so many spare parts, (and do not want to spent 400 on heads shipped) that I am going to try and slap the EA81 heads and parts onto the EA71 block.. If that fails, I'm going to swap an EA81 motor in. I'll make sure to let you guys and gals know what the outcome is!

 

THis is a very slow moving forum.. Still better than NASIOC.. Just suppose it means that these cars are a rare find on the road... lol.. Too much love for the stars

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  • 8 months later...

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