Backfiring, shaking idle, and more.. - Ford Bronco Forum
 
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post #1 of 11 (permalink) Old 05-19-2017, 01:15 PM Thread Starter
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Backfiring, shaking idle, and more..

Having issues with my truck. I ran codes but nothing came up too drastic in KOER test (172,225,632) and with KOEO i got (334, 327,and 539) Im pretty sure some of those codes may come from my badly cracked exhaust manifold, but those codes are not necessarily the issue, because i've had those codes since I've owned the truck, but it has still ran fine, until yesterday.

The idle seems to be shaking alot more now, the rpm needle shakes alot at idle now also. It hunts for a second or two (always did this) but once it settles down i can feel the truck shake and see the rpm needle shake as well.

While driving at slow speeds nothing is noticeable. Around 35-40 mph after a downshift into third I believe, the whole truck shakes and i can hear a faint backfiring or popping noise. At a certain speed this goes away (above 55 maybe), but if i let off the acceleration a bit and pick back up, it starts the shaking and popping cycle starts again.

I was thinking that I may could be the TPS sensor, but im not too sure. Im wondering if these symptoms sound like that would be the problem.


Thanks guys

1992 Ford Bronco XLT Nite
Lifted on 36's
Tonneau soft top.
& whatever the previous 12 owners felt like tinkering with.
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post #2 of 11 (permalink) Old 05-19-2017, 02:30 PM
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I'll bet that cracked manifold has grown and is not creating a bigger issue. Every heat and cool down cycle hurts a crack, and all it will do is grow. Otherwise I'd look at your timing. Maybe the hold down for that distributor got loose and it has turned a little on you.


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post #3 of 11 (permalink) Old 05-19-2017, 03:21 PM
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You know about a progressing large crack in your exhaust manifold and yet you discount it as the source of your running issue because "it's been there a while"? You know how silly that sounds, correct?

A new manifold is less than $70 shipped to your door, depending on the side. Fix a known issue and then decide if you have another.

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post #4 of 11 (permalink) Old 05-19-2017, 03:42 PM
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Quote:
Originally Posted by pollux View Post
You know about a progressing large crack in your exhaust manifold and yet you discount it as the source of your running issue because "it's been there a while"? You know how silly that sounds, correct?

A new manifold is less than $70 shipped to your door, depending on the side. Fix a known issue and then decide if you have another.
x2
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post #5 of 11 (permalink) Old 05-19-2017, 06:17 PM
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codes
172- I'm not sure what priority the O2 has in this vintage of Ford but I do know most cars on the road are controlled by computers that make O2 sensors pretty high on the priority list. In other words, this could very well cause performance issues.

225- Knock sensor. The definition says to ignore if not pinging but it wouldn't hurt to diagnose this code regardless.

632- "E4OD Transmission Control Switch (TCS) should be cycled once between engine ID and Goose test"
I don't even know what the hell this means.

334- 'EVP sensor high..." This seems unlikely.

327- "EGR feedback signal low". EGR issues can absolutely affect performance. Pay special attention to this one. Although, there being a manifold leak (possibly less exhaust going to EGR) may be the reason for this. Just a guess.

539- "System shows voltage at PCM pin 10 Is A/C on ?" Well, is it? I don't know. not familiar with this one.

I agree with MATCHBOX. Take care of known repairs needed first then go from there.

"Oh man, lodged where??"
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post #6 of 11 (permalink) Old 05-19-2017, 06:20 PM
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Update on code 172

code #172- "Oxygen sensor not switching system is or was lean Single, Right or Rear HO2S Fuel control"

Here, read it again...

"Oxygen sensor not switching system is or was lean Single, Right or Rear HO2S Fuel control"

"Oh man, lodged where??"
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post #7 of 11 (permalink) Old 05-19-2017, 06:52 PM
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Originally Posted by mrnewland1 View Post
632- "E4OD Transmission Control Switch (TCS) should be cycled once between engine ID and Goose test"
I don't even know what the hell this means.
It means the KOER test procedure was not completed correctly. It's expecting input from the driver to test signals and sensors and they were not perceived by the EEC module.

http://www.corral.net/tech/maintenan...koer.html#koeo

Quote:
This test requires up to three inputs from the driver during the test. The first input requires that the brake pedal be depressed, the second requires that the steering wheel be turned at least one-half turn and then released. Finally on cars equipped with an E40D automatic transmission, the Overdrive Cancel Switch (OCS) must be deactivated, then reactivated.

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post #8 of 11 (permalink) Old 05-19-2017, 08:21 PM
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Quote:
Originally Posted by pollux View Post
It means the KOER test procedure was not completed correctly. It's expecting input from the driver to test signals and sensors and they were not perceived by the EEC module.

http://www.corral.net/tech/maintenan...koer.html#koeo
Ah ok. i have a similar test (optional test while hooked up to old scan tool) on my '89 that includes turning lights on, pressing brake pedal and turning steering wheel. I don't know, maybe it's the same test but not as advanced. My truck is has a C6 (hopefully not for too much longer).

"Oh man, lodged where??"
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post #9 of 11 (permalink) Old 05-19-2017, 11:50 PM Thread Starter
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thanks or the responses. Im working on getting the manifold replaced but it costs a little more than I can spend at the moment. I was quoted around $450. I rarely drive the truck more than 25 miles a week at the most. Its just not cost effective right now when I have a Mazda that gets 41mpg. lol But, The reason I was asking about the TPS was because this issue just started out of nowhere this week. I remember vaguely about a week ago the check engine light came on, but went off never to come back, so I figured it was nothing. Nothing showed up in the code check other than the same ones above.

Im wondering if it is possible to remove/unplug the TPS from the TB to see if it would run better. All post i've read seem to state that you have to remove the whole assembly to access the TPS. I forgot to mention i'm not mechanically inclined -_-

1992 Ford Bronco XLT Nite
Lifted on 36's
Tonneau soft top.
& whatever the previous 12 owners felt like tinkering with.
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post #10 of 11 (permalink) Old 05-20-2017, 08:57 AM Thread Starter
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I think I may have solved the problem. I unplugged the TPS and compared a test run with and without it. With it plugged in, it hunts to idle and the car stutters and backfires after the shift to third. Without it plugged in, the idle dropped , and no backfiring or stutter. Although it does shift late and/or hard but i think thats just a symptom of having the tps unplugged.

About to order a new one, im assumimg the motorcraft one works best? or could I get away with a BWD brand?

Thanks for the help guys

1992 Ford Bronco XLT Nite
Lifted on 36's
Tonneau soft top.
& whatever the previous 12 owners felt like tinkering with.
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post #11 of 11 (permalink) Old 05-20-2017, 10:18 AM
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Yo Cal,
Go with the Motorcraft TPS every day.
I buy my Ford parts via AMAZON; they are VG at delvy and esp pricing; A few years ago I bought a $150.00 DPFE Sensor (not incl. sales tax) for $50.00 with free shipping and no state sales tax; same for the IAC sensor.

Some buy from a Ford pn from on-line or local parts stores that list the Ford PN, but the ads show the PN as a reference only and the supplier may be a company off-shore. other than a Ford supplier.

Throttle Position Sensor (TPS) Overview & Testing by Seattle FSB

For no RELEVANT backfire @ idle codes, Ford's usual perpetrators are;
Vacuum Leaks; see my Vacuum leak test in post #11
Check spark plug wires and routing.

See my partially recovered Bronco web site ...Will need to clean up dead links & add many more new links some day. Thanks to Mr. Schwim!
THANKS to ALL WHO SERVE!
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