A Super-Ultimate 3FE Diagnostics Thread - Let the Battle of Wits Begin (2 Viewers)

OSS

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That beat up Tekpower 188 meter you're using costs $9 new. That means it probably cost $3 to manufacture in China (maybe $1.50).

1. Throw it in the trash
2. Buy a decent meter that costs over $60.

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I hear what you are saying about the idle when you jump the terminal while setting timing, but maybe the fact that your idle drops a lot is due to the underlying issue... that, and don’t gauge rpm by sound of idle...; check the tach... if you were supposed to adjust the idle speed yourself when checking time the fsm would say so...
 

lelandEOD

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That beat up Tekpower 188 meter you're using costs $9 new. That means it probably cost $3 to manufacture in China (maybe $1.50).

1. Throw it in the trash
2. Buy a decent meter that costs over $60.

View attachment 1641491

I know it’s a POS. I only bought it to check the needle fluctuation specifically for the O2 sensor voltage test. I don’t think it necessarily needs to be accurate, does it? Just needs to deflect so I can make sure there are more than 8 pulses in 10 seconds.

For everything else, I’m using a Fluke 87 DMM.

I hear what you are saying about the idle when you jump the terminal while setting timing, but maybe the fact that your idle drops a lot is due to the underlying issue... that, and don’t gauge rpm by sound of idle...; check the tach... if you were supposed to adjust the idle speed yourself when checking time the fsm would say so...


I will readjust the timing without manipulating the idle and see what happens. It’s my understanding that by jumping the check connector pins you are overriding the ECU’s altitude compensation? I’m at 4500 foot elevation so I don’t know if the 100 – 150 RPM drop in rpm is appropriate or not.
 
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lelandEOD

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Default to not doing things not directed by fsm. With the idle xception of a few omissions, they are spot on...

I hear ya. But I have no idea what to do when I run into a situation where the FSM doesn't provide information on what to do in situations like this. It just says: Warm up engine. Connect timing light. Jump terminals TE1 - E1. Check idle speed at 650 rpm. Set timing to 7° BTDC w/ TE1-E1 connected.

This engine idles at 650rpm when warm but when I jump TE1 -E1, it drops the idle another 100-150rpm. So, what should I do? Time it at ~500rpm even though it says 650rpm or increase the throttle to keep it at 650rpm while I set the timing?
 
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If you must I would shim the throttle open to get there. At least the air is metered this way. Adjusting the golden screw or something else will confuse the confuser.
 

lelandEOD

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If you must I would shim the throttle open to get there. At least the air is metered this way. Adjusting the golden screw or something else will confuse the confuser.

Makes sense to me, thanks!





Also, I conducted the resistance tests on FI-79 with some strange results.

Basically, everything checked out according to the FSM with the exception of the intake air temperature (THA-E2). With the intake at 68°F, I was supposed to get 2,000-3000 ohms and I got 7750 ohms.

I tried several AFMs and got the same resistance reading on all three AFMs so I don't think this is a problem related to the AFM. I also put a hair dryer in front of the temp probe to see if the fact that it was about 55°-60°F in the garage made a difference. No joy.



IMG_6301.JPG
 
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Makes sense to me, thanks!





Also, I conducted the resistance tests on FI-79 with some strange results.

Basically, everything checked out according to the FSM with the exception of the intake air temperature (THA-E2). With the intake at 68°F, I was supposed to get 2,000-3000 ohms and I got 7750 ohms.

I tried several AFMs and got the same resistance reading on all three AFMs so I don't think this is a problem related to the AFM. I also put a hair dryer in front of the temp probe to see if the fact that it was about 55°-60°F in the garage made a difference. No joy.



View attachment 1642191
Is it the wiring? What is your THA-E2 at the AFM connector? Also curious what the THA-E22 resistance reads and the E2-E22 reads at the ECU.
 
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Seems like the resistance check on that page should be from THA-E22. That wire leaves the AFM as E2 but comes into the ECU at E22. If we are checking the wiring from the AFM to ECU, wouldn’t that make sense or am I screwed up?
 

lelandEOD

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Seems like the resistance check on that page should be from THA-E22. That wire leaves the AFM as E2 but comes into the ECU at E22. If we are checking the wiring from the AFM to ECU, wouldn’t that make sense or am I screwed up?


I know, it’s confusing, right? The resistance test specifies THA-E2 at the ECU terminals, but the digram on FI-36 shows THA - E22 between the ECU and airflow meter. Do you think there’s a reason the resistance test specifies THA –E2 as opposed to E22 or could it be a typo?

6A51CBAA-1554-4B49-8FD0-EA3B14CC30BE.jpeg
 
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FJ40Jim

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It just says: Warm up engine. Connect timing light. Jump terminals TE1 - E1. Check idle speed at 650 rpm. Set timing to 7° BTDC w/ TE1-E1 connected.

This engine idles at 650rpm when warm but when I jump TE1 -E1, it drops the idle another 100-150rpm. So, what should I do? Time it at ~500rpm even though it says 650rpm or increase the throttle to keep it at 650rpm while I set the timing?

Just set the timing as normal. When the test connector is jumpered, the timing map is locked out and the ignition is firing off the distributor directly. The rpm doesn't matter.
 
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I know, it’s confusing, right? The resistance test specifies THA-E2 at the ECU terminals, but the digram on FI-36 shows THA - E22 between the ECU and airflow meter. Do you think there’s a reason the resistance test specifies THA –E2 as opposed to E22 or could it be a typo?

View attachment 1642254
The wiring diagram shows it as E22 at the ECU as well.
 

lelandEOD

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Anyone know the part number for the Denso O2 with the long pigtail/harness? I've got the new bungs/blanking plates on order, but I'm pretty sure I'm going to need new O2s with longer wiring to reach further downstream.
 

Kleatus

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Anyone know the part number for the Denso O2 with the long pigtail/harness? I've got the new bungs/blanking plates on order, but I'm pretty sure I'm going to need new O2s with longer wiring to reach further downstream.
I am using Denso 234-4056 with no issues - not factory exhaust but if I remember right I put them the same distance downstream and the wires reached fine.
CDB5A529-2419-4234-BD35-9CCB0BC9D3F8.jpeg
 

lelandEOD

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I am using Denso 234-4056 with no issues - not factory exhaust but if I remember right I put them the same distance downstream and the wires reached fine.
View attachment 1642892

Good times!

I need to get my hands on the longest possible O2s because the harness on my truck was butchered when I got the cut front-clip with the 3FE. Whoever torched the engine/frame cut through the O2 harnesses above the connectors so I had to source new harness-side plugs for the O2s from the 'mud classifieds. I think they are probably shorter than they were originally (at least the one that drops between cyl 3-4). So, I need all the extra length I can get.
 

lelandEOD

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I fashioned a home made smoke testing machine and tested the engine last night. There is a leak at the ISC valve. I don't think this leak is serious enough by itself to cause the lean-miss, but it was an interesting experiment.

I also installed the one AFM I have that's had the top cover removed before. I played with the large toothed wheel in there and was able to get the warm AFR set to my preference. I set it to 14:1 and noticed a good deal more pep to the engine in a quick hop around local roads. I had this AFM on the engine when I smoke tested it. It was interesting that the AFM top plug can also be the source of a vacuum leak if the RTV seal is compromised. Check out this video:


Tweaking the AFM calibration is just a bandaid covering the real problem so the troubleshooting will continue... New O2s and bungs should be here by next week.
 
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There is an O ring inside the idle speed control that's probably old and dried up. Just have to undo the three phillips screws that hold the black plastic cylinder to the housing.

The size is 2mm x 36mm - I used a V75 Viton O ring

Dont give up - this thread will be incredibly helpful for many!
 

lelandEOD

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There is an O ring inside the idle speed control that's probably old and dried up. Just have to undo the three phillips screws that hold the black plastic cylinder to the housing.

The size is 2mm x 36mm - I used a V75 Viton O ring

Dont give up - this thread will be incredibly helpful for many!

Thanks for the tip. I've got a new O-ring on order!
 
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lelandEOD

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Played with it some more today.

I don't know how successful relocating the O2 sensors will be due to the configuration of my exhaust. I pulled it down today and there is not a lot of room to play with before the collector. I can easily place the O2s anywhere on the down tube but that doesn't really get me much father than where they are right now. The part of the pipe where it turns horizontal is too close to the flywheel/bell housing and there isn't room to fit these big bulky sensors.

So, I'm faced with a dilemma. I either put the O2s at the bottom of the down pipes or I have to have a new exhaust system fab'ed up with the collector closer to the muffler.

Thoughts?

IMG_9373.JPG
 

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