AFR Issues

[Eric Sy GN]

Re: AFR Issues

From that log, it didn't look like you were waiting long enough for the ECM to power down. The ECM needs to power down do it can reset the TPS position (the auto-zero) on the next power up. You can see in the log that your TPS % was rarely under 1%, which means it is probably staying in throttle follower mode which gives you higher IAC readings. When you turn the key off, wait 10 seconds. When you turn the ignition back on, look to see that the TPS % is under 1%.
There was one point were it was at .4%, but then you blipped the throttle and it was stuck at 1.2% after that, so something is hanging it up.
If all else fails, I can move the idle TPS threshold in the chip program, but I don't normally need to do that.

 

[Static]

Re: AFR Issues

Doesn't explain how it migrated so far from its original set point. I was able to obtain 30 when I first set this up. Well I guess I will try again tomorrow.

 

[Static]

Re: AFR Issues

Well played with it again today with no success. Started with the screw fully out. Turned in 1/2 turn increments waited 20 seconds for power down. IAC counts go up. Went the other direction. IAC counts go down. Removed the cruise control cable, eventually I run out of adjustment screw. Got super rich. Actually saw less that .4% TPS. Got to low 60s on counts. Patching the chip seems to be a band-aid? I would like to figure out what is actually going on and why I am having the exact opposite behavior of whats expected. I appreciate the help and input I've got thus far. Here is a log from today https://onedrive.live.com/redir?resid=7B2B331058212480!335&authkey=!APBP9-omCQFfSH8&ithint=file%2cuni

 

[Don W.]

Re: AFR Issues

What would happen if the wires to the IAC somehow got switched? Either end? I'll get you the sequence.

 

[Don W.]

Re: AFR Issues

At the IAC looking at the plug with the clip to the left; upper left is lt blu/wht, upper right lt grn/blk, lower right lt grn/wht, lower left blu/blk.

lt = light

At the ECM, look at the large connector (the one with more wires. I left out colors here because, at least in mine, the colors don't match.)

on the clip side

E3 lt grn/wht
E4 lt grn/blk
E5 blu/blk
E6 lt blu /wht

 

[Static]

Re: AFR Issues

Thanks Don. Im going to pull the IAC tomorrow and test it out of the TB and see what might be going on. I will check the wiring as well. I have a spare from something (possibly TPI or TBI) sitting on the shelf, Ive plugged it in before so I know its keyed right for SYTY. Are the pinouts the same for all these style IACs?

 

[Don W.]

Re: AFR Issues

All can say is that they are the same within Syclone's. Only because, as you might have figured, I have the wiring diag. If I say it applies to the Ty I'll probably have to remove my foot. :rotf:

While you have all this apart it's probably a good idea to not only check pin-outs but also check continuity. Also check for shorts to ground.

 

[Static]

Re: AFR Issues

Ok removed the throttle this morning to inspect the IAC passage for cleanliness and test the IAC function. I ended up replacing it with the one I had on the shelf. Seemed that maybe the plunger moved further out than the one that was already on the truck. I ran out of trials of Datamaster, so I switched to Tunerpro using Erics ADX for the TT chip. Started with the screw all the way out and adjusted in 1/2 increments. I was in the low 50s and I started seeing some really wacky TPS values. At the very end of the log I actually unplugged the TPS and it went full lean on the wideband. I snapped a pic of the wiring and the part number of the IAC I pulled out. Is it an original?
Log here

 

[Static]

Re: AFR Issues

Been a while since I had time to work on this. I had to replace a blown intake manifold gasket on a friends second gen 4.3. I ordered the parts from rock auto and also picked up a new TPS sensor for the TY while I was there. Got it changed out and now my IAC counts are down to 27-29 where they should be. The TPS voltage is low now however. How should I go about bringing that up?

Log1
Log2

 

[Static]

Re: AFR Issues

Well I took the TPS and slotted the holes so I could adjust the sensor to get more voltage at idle and at .61 volts it idles at 1900 rpm and the IAC is 140. So that didn't work. Anyone have any input? Seems to run fine otherwise with the low TPS voltage

 

[Eric Sy GN]

Re: AFR Issues

What is the TPS % at idle? TPS % is more important than the voltage. Should be under 1%. Blip the throttle and make sure it comes under 1%. If not, I can change the threshold to, say, 2% in the chip. (The threshold that switches between idle control and the throttle follower.)

 

[Davemc1963]

Re: AFR Issues

You could try carefully bending the tps operating lever at the 90 degree. Obviously you will have to hold the lever and not the housing whilst doing this.

 

[Static]

Re: AFR Issues

What is the TPS % at idle? TPS % is more important than the voltage. Should be under 1%. Blip the throttle and make sure it comes under 1%. If not, I can change the threshold to, say, 2% in the chip. (The threshold that switches between idle control and the throttle follower.)

It was 9% at .61 volts. Its not auto zeroing either if I shut the truck down.

 

[Eric Sy GN]

Re: AFR Issues

Maybe try pulling power to the ECM to reset its memory. However, you shouldn't have to do that.

 

[Static]

Re: AFR Issues

I will try that. I will have to get all my TT settings before I do this as it will lose memory as well.

 

[Static]

Re: AFR Issues

Well the truck is back to misbehaving again. I changed out the TT chip last month and everything has been good up until this point. Took it on a 60 mile long drive Saturday, nearly all freeway 70-80 mph A/C on. Was 110 out truck was running 220 as it usually does when the a/c is on. Exited the freeway and came to the stoplight and it started running rough and went to 10.2 on the afr. I 2 footed it to keep it running and at the next light it stalled. Started right back up and drove for 5 miles on side streets, no stops were made. Heavy fuel smell shortly after exiting the freeway. Parked in front of the house and let it idle in park for 5 minutes while I looked under the truck and in the engine compartment for fuel. Couldn't see anything. I did for some reason take the fuel cap off and got a pretty good hiss from it. Started it up to leave and blew a nice cloud of fuel. Drove home with the gas cap off no issues. Made 1 stop and left it running when I went in to the store. So possible vapor lock, too much pressure in the tank?

 

[Don W.]

Re: AFR Issues

Is your canister hooked up correctly so the tank can vent? I had a fuel smell and the line from the tank that comes through the frame and connects to the hose to the canister had come off.

 

[Static]

Re: AFR Issues

Where is the canister for these trucks? I don't remember seeing one.

 

[Mr K]

Re: AFR Issues

Left side under air filter

 

[Static]

Re: AFR Issues

Well I do not see anything obvious with the eavp system. The vacuum line is hooked to the TB, the check valve is the right direction and works. The line to the tank is clear and holds pressure. I pull the cap off and the pressure relieves. The cap is vented and works one way(air is let in to the tank). The canister itself seems to be connected correctly. There is a 3rd port that has some sort of cap that is supposed to be vented and leaks a bunch of air? Probably where the heavy fuel smell was coming from. So Im guessing hot day, hot fuel coming back to the tank caused the system to over pressurize forcing excessive vapor into the evap system and back into the TB causing extreme rich condition?