HELP! Wideband is reading lean at idle!!!

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Stupuff

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I've got a 2004 R/C SRT10 Ram with a ROE camshaft and the Lysholm 3.3L/ROE supercharger ontop.

at idle my wideband is reading 17+ and my intake pressure is around 4"....

As far as I can tell I don't have an intake leak. I've checked the resistance on all my injectors (16.6-16.8). My fuel pressure (at the rails) is 58psi. Not getting any misfire codes (yet...) but clearly misfires under boost.

I checked out my Short Term Fuel trims (bank 1&2) and the PCM is pulling fuel away...

I was thinking that I had vacuum leak somewhere but if I did the PCM would be adding fuel, not taking it away...

Any ideas? I'm stumped...
-Stupuff
 
Compression & leak down test time. You have un burned fuel going down the exhaust pipe.
 
The o2 sensors are all new (all 4). I'm going to do a compression & leakdown test. I'll let you know what I find.

I've checked all the PCM inputs and they seem to check out (TPS, MAP, o2's, CT & IAT).
If my numbers are good on the compression test (fingers crossed) I'd be thinking computer next? I dunno... we'll see after the comp' test.
 
What brand wideband? What controller?
I've seen many that show lean at idle and I believe it's lack of airflow across wideband O2. If you barely give it gas does it bounce above and below 14.7 constantly? If so you're good bud. If you are showing boost at idle and PCM tune isn't adding fuel to compensate than I can see a lean idle.
 
Check your bypass valve at the rear of the Roe. You should not have boost at idle - if so your vacuum signal to the bypass valve is bad. If you do have boost at idle your fuel maps at the lower RPM is not setup (and probably shouldn't be) for the extra air and your trims can't adjust enough.
 
Stupuff said:
I've got a 2004 R/C SRT10 Ram with a ROE camshaft and the Lysholm 3.3L/ROE supercharger ontop.

at idle my wideband is reading 17+ and my intake pressure is around 4"....

As far as I can tell I don't have an intake leak. I've checked the resistance on all my injectors (16.6-16.8). My fuel pressure (at the rails) is 58psi. Not getting any misfire codes (yet...) but clearly misfires under boost.

I checked out my Short Term Fuel trims (bank 1&2) and the PCM is pulling fuel away...

I was thinking that I had vacuum leak somewhere but if I did the PCM would be adding fuel, not taking it away...

Any ideas? I'm stumped...
-Stupuff
Click to expand...

check the coupler on the rear of the roe, but it will hunt at idle regardless the brand, only time to really read the air /fuel is at wot
 
its an AEM wideband and a VEC3 controlling fuel

*fyi: I bought this truck with everything it has except the competition coupe cam. I had to get the cylinder heads re-done because I had installed e3 spark plugs and the cages blew apart and stretched some valves.... SPI in Oakville Ontario redid the heads put it back together and claimed it had 698hp at the wheels on the dyno. Except its never ran properly since...

I had made complaints to SPI about the drivability and they said "I must have done something". Typical... That rebuild was NOT cheap. I paid in full and since then I've had to replace my clutch and supercharger snout ass because of some really harsh misfires...

At the moment its together after having the supercharger snout rebuilt and its currently "running". That's all the info I can give you guys at the moment. Thanks a lot for any and all input. I'm literally trying everything suggested.

THANKS AGAIN GUYS!
 
Just did a compression test on all cylinders they are all close to 150psi.

Will try to post a video of it running soon.
 
Take the vec 3 off and throw it in the trash, I know it's been a continuous problem on that truck. If you have the coin go with an AEM infinity stand alone eco, looking at 5k, if not use the stock ecu and an sct to tune it
 
as he says, too much wiring to do on the vec unless you have a degree in electrical, dump it go with sct, tenability is much better
 
the stock pcm controls the engine at idle. the vec "should" only be affecting trim when it sees boost right?

this all seems to have started when I had the camshaft installed. I'm starting to think that the cam isnt' fazed correctly with the crank and the pcm is trying to compensate. just a guess of course but...

How do I put the engine into base timing so I can throw a light on it to confirm proper cam clocking?

SCT, is that the plug and play on that connects to the OBDII port?
 
If you are getting boost at idle you should look into that first. Your first post stated you were seeing 4# and you shouldn't have that - unless I completely misunderstood your post.
 
seethrough said:
If you are getting boost at idle you should look into that first. Your first post stated you were seeing 4# and you shouldn't have that - unless I completely misunderstood your post.
Click to expand...

I think he meant 4" of vacuum.
 
VPRPWRD said:
I think he meant 4" of vacuum.
Click to expand...

I thought that at first but then when I reread it he stated 4# of pressure. Maybe I am assuming too much but if the bypass valve is not opening you will get pressure at idle and a lean condition. Maybe the OP can shed more light on the symptoms and clear this up.
 
Stupuff said:
the stock pcm controls the engine at idle. the vec "should" only be affecting trim when it sees boost right?

this all seems to have started when I had the camshaft installed. I'm starting to think that the cam isnt' fazed correctly with the crank and the pcm is trying to compensate. just a guess of course but...

How do I put the engine into base timing so I can throw a light on it to confirm proper cam clocking?

SCT, is that the plug and play on that connects to the OBDII port?
Click to expand...

The SCT is a plug and play that connects to the OBDII port. Sean Roe can get you a canned tune that will be close for your setup and then you can get with a dyno facility and Torrie for a more exact tune. If you just had the cam installed and are concerned about phasing you will probably have to degree it to find out how it is installed. Another thing that you can check on these Roe set ups is the MAP sensor. Not sure about the VEC setup but I had all kinds of problems with mine and eventually got another new MAP sensor to clear the problem.
 
Ok, so here's the update (had a friend look at it with us):

We started it last night, let it get to temp.

First thing we noticed is it looks like my vacuum/boost gauge is wrong. i'm not getting 4" of vacuum like previously thought. I'm actually getting 12" (at idle). We were able to verify what the pcm was seeing with a scan tool. When going down the road we're seeing around 18-20". Let me know what you guys think about that...

Second thing we noticed is the wideband was still reading lean, even though i know its running rich (tail pipe smelled of raw fuel at idle and my rpms are 750 and steady). This condition is only at idle it seems... On the road the readings are very good (low 11s to high 13s). It does go lean sometimes but at normal times...

Third thing: I tested the valve on the back of the supercharger and it tested ok

After the drive there were no stored codes, no misfires and made it to closed loop operation. We made 10psi of boost consistantly (2 pulls...). Not sure what its supposed to make for boost tho as this truck has been nothing but problems for the last 2 years...

I believe its running MUCH better now that I gave the PCM a chance to learn but i'm not 100% sure because of the wideband readings. I just can't risk it...

Q: I'm wondering if the pcm is pulling fuel back 30% at idle to compinsate for the larger injectors. Also i'm wondering about wideband sensor placement. How far back should it be from the engine? Just want to make sure its in a prime location and isn't getting false readings.
 
Stupuff said:
Ok, so here's the update (had a friend look at it with us):

We started it last night, let it get to temp.

First thing we noticed is it looks like my vacuum/boost gauge is wrong. i'm not getting 4" of vacuum like previously thought. I'm actually getting 12" (at idle). We were able to verify what the pcm was seeing with a scan tool. When going down the road we're seeing around 18-20". Let me know what you guys think about that...

Second thing we noticed is the wideband was still reading lean, even though i know its running rich (tail pipe smelled of raw fuel at idle and my rpms are 750 and steady). This condition is only at idle it seems... On the road the readings are very good (low 11s to high 13s). It does go lean sometimes but at normal times...

Third thing: I tested the valve on the back of the supercharger and it tested ok

After the drive there were no stored codes, no misfires and made it to closed loop operation. We made 10psi of boost consistantly (2 pulls...). Not sure what its supposed to make for boost tho as this truck has been nothing but problems for the last 2 years...

I believe its running MUCH better now that I gave the PCM a chance to learn but i'm not 100% sure because of the wideband readings. I just can't risk it...

Q: I'm wondering if the pcm is pulling fuel back 30% at idle to compinsate for the larger injectors. Also i'm wondering about wideband sensor placement. How far back should it be from the engine? Just want to make sure its in a prime location and isn't getting false readings.
Click to expand...

Starting to sound better now. You should read vacuum at idle and cruise! Your numbers look reasonable. The rich idle can be due to the injector sizing and tune mapping at idle. Wideband should be around a foot from collector of header. It also should be mounted inverted as to not let moisture collect on sensor. It also shouldn't ever be used without power. It will contaminate sensor.
You should see bouncing above and below 14.7 during light cruise. When you mash the gas, it should stay pretty solid around 11.5-12 unset boost. You may need to video this as it's hard to watch the road and monitor.
Guess I'm lost but whose truck was this? Oh and if you're making 10lbs they Roe has been pullied!
 
How did the plugs look when you did the compression test ?
How did the truck run before the new cam install ? and did you get a new card programmed after you installed it ? If you got the cards from Sean they should say how many degrees have been pulled on them (and injector size), I saw you posted you're at 10 lbs. ?!? and if that is right you should have a 9-10 card...

You can measure your pulley diameter to find out what # you have... Sorry I don't have any answers about your lean condition but I would be more worried about backfires and detonation at WOT then the idle issues
 
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