Only 2K RPM Misfire - '84 2m4 Iron Duke (Page 2/2)
Sanhino JUL 27, 11:35 AM

quote
Originally posted by andreww:


Shouldn't the fuel pressure be over 34PSI?



If I remember correctly it should be that high if it was a V6 or later model but for the 84 iron dukes 10-12 psi is normal. (Someone more familiar please correct me if I'm wrong).
Sanhino JUL 27, 11:47 AM

quote
Originally posted by andreww:

A video would be very helpful here.



https://imgur.com/gallery/v0o5BHi

There are 3 videos there: One of throttle body, one of fuel pressure, one of tach (all not the same run of course). The spray pattern looks a lot worse in the video than it does in actuality, I think it's how my phone captures the video. It only seems to capture some of of the sprays.

[This message has been edited by Sanhino (edited 07-27-2020).]

Nickoman JUL 29, 03:27 PM
Absolutely dumb question. But did you get all 4 plug wires back on the right hole? I'm only asking because I've in my ultimate wisdom......... have put wire 2 on plug 3 and 3 on 2... and I checked timing on holes 1 and 4... thinking I had no ignition timing issues. https://www.youtube.com/watch?v=ZT0GOnz-AwM don't mind the whining noise that was a brand new timing gear doing its thing.
Nickoman JUL 30, 01:12 PM
Never mind I just re read your initial subject line. It drives fine other than the specific RPM range. 2 dead holes would not handle that! Im dumb!!!
Shho13 AUG 07, 10:27 PM
I have a V6; never had a 4 cylinder Fiero and am too lazy to look it up if the 2.5 has an EGR as well; I had an issue with my EGR valve where it would stick and nearly stall out on returning to idle like it seems to do in your video...

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Sanhino AUG 11, 10:16 AM

quote
Originally posted by Shho13:

I have a V6; never had a 4 cylinder Fiero and am too lazy to look it up if the 2.5 has an EGR as well; I had an issue with my EGR valve where it would stick and nearly stall out on returning to idle like it seems to do in your video...




I had checked previously if it slid when under vacuum. It does (or at least did when I checked it) but I ordered a new EGR and gasket regardless. Maybe under idle vacuum it runs fine but slight vacuum at 2K rpm isn't enough to move it, and then higher RPMs are able to move it.. just spit balling at this point. Or maybe it's just crunchy and doesn't slide like it's supposed to. I order a new PCV valve too since that's still original and it's cheap enough.

I was also looking up videos of GM single carb throttle body rebuilding. If I was to replace the injector I would already be halfway to replacing the fuel pressure regulator so maybe that's worth trying too? Maybe I'll do that if the new EGR and PCV doesn't make any difference.
Sanhino AUG 15, 12:24 PM

quote
Originally posted by Shho13:

I have a V6; never had a 4 cylinder Fiero and am too lazy to look it up if the 2.5 has an EGR as well; I had an issue with my EGR valve where it would stick and nearly stall out on returning to idle like it seems to do in your video...




I just replaced the EGR and the PCV valve and it seems to have fixed it, no specific misfire at 2K rpm and if I hold it and release the throttle it doesn't stall out like it used to. I'm so excited!