1986 Bronco II Engine Problems
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1986 Bronco II Engine Problems
Hello,
I have a 1986 bronco II that runs, but at a terrible speed. The most it will do is 35 max, and is a total dog on hills. It does run sometimes at higher speeds, but quickly falls back to 35 mph max.
It gives 25 & 77 codes when I pull the codes it has.
Fuel pumps are new, so those shouldn't be a problem I would think. It ran fine before, but after taking it to a smog place that "tweaked" some stuff under the hood (no idea, I didn't take it in) it runs like heck now.
i'll try and get some more information later, this is all I know at this point.
Any ideas?
Thanks,
Dane
I have a 1986 bronco II that runs, but at a terrible speed. The most it will do is 35 max, and is a total dog on hills. It does run sometimes at higher speeds, but quickly falls back to 35 mph max.
It gives 25 & 77 codes when I pull the codes it has.
Fuel pumps are new, so those shouldn't be a problem I would think. It ran fine before, but after taking it to a smog place that "tweaked" some stuff under the hood (no idea, I didn't take it in) it runs like heck now.
i'll try and get some more information later, this is all I know at this point.
Any ideas?
Thanks,
Dane
Post Fiend
Joined: Dec 2001
Posts: 10,562
Likes: 4
From: South Jersey
Welcome to FTE!!!
The 25 is a knock senser code, you should run the pinpoint tests before repalcing anything.
The 77 indicates you didn't "goose" it when required, try running the test again.
Could also be a clogged cat, hook up a vacuum gauge, bring it up to 2500rpms for a few minutes, if the vacuum starts to drop you MAY have a clogged cat.
The 25 is a knock senser code, you should run the pinpoint tests before repalcing anything.
The 77 indicates you didn't "goose" it when required, try running the test again.
Could also be a clogged cat, hook up a vacuum gauge, bring it up to 2500rpms for a few minutes, if the vacuum starts to drop you MAY have a clogged cat.
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
In my experience, both a KOER 25 and 77 are both related to an inadequate "goose" for the goose test. Like Ken said, try the KOER test again, being sure to hit the goose strong at the correct time and see if those codes go away. In addition, since you don't list other codes, can I assume that you got pass codes for the KOEO and CM portions of the self-test?
Additional things to check:
Cat clogged?
Fuel pressure correct? Gas in vacuum line to fuel pressure regulator (FPR)? Gas = bad FPR.
Ignition base timing correct (10-12 BTDC with SPOUT removed)? Timing advance working correctly (Tested with SPOUT connected as part of KOER test)?
Additional things to check:
Cat clogged?
Fuel pressure correct? Gas in vacuum line to fuel pressure regulator (FPR)? Gas = bad FPR.
Ignition base timing correct (10-12 BTDC with SPOUT removed)? Timing advance working correctly (Tested with SPOUT connected as part of KOER test)?
Postmaster
Joined: Dec 2001
Posts: 3,742
Likes: 2
From: UT
I don't understand it thoroughly myself. One of the first time I tried the KOER test on my BII, I got the 25, which my manual linked to the knock sensor not tested during goose test. I repeated the test, being sure to give it a stronger goose, and the 25 went away. I think it has to do with the fact that spark knock shows up more as the engine works harder. I think the idea is to make the engine work hard enough during that brief "goose" to get a little bit of ping for the knock sensor to respond to.
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