Why is it lean on passenger side?

[Spud]

I still have a situation where the passenger side runs leaner than the driver's side. I've had threads before and have followed advice from those and then some, and it still exists...

I have a TT 97 cobra with an Aeromotive fuel system complete to the rails and back. I've had the injectors inspected and cleaned, no difference. I've replaced and rewired the entire ignition system, no diff. I've even tried wiring COP modules from my dual pack system to waste, no diff. I've sent my FAST ECU back to FAST to upgrade to SEFI and added indiv. cyclinder control hoping just switching to SEFI would do it. I thought at first it did, but that made no diff either. I've cured a couple anomalies with the help of some of you (Craig for instance) with such things as my injector harness pinout being wired incorrectly (was wired standard GM as opposed to small block Ford firing order). Thought that would do it too, but no. I'm running a custom sheet metal intake on it now, but this problem existed previously.

What I'm thinking now is this: Because it's a 4 cam engine, and the degreeing of the cams is so crucial, it may be that the passenger bank is off a bit causing it to burn slightly leaner. I do have one cylinder that's a bit lower in compression testing, but not more than 10% of the adjacent cylinders which is acceptable to Ford. I added fuel in that cylinder and it didn't make much difference, so I added 5% to all cylinders on the passenger side, and that brought the AFR to match the driver's side. My question is if the intake or exhaust cam on the passenger bank was off slightly enough to cause this anomaly, would that show in the compression test??? BTW, I've done a leak down test as well which checked out fine. Also, I have reliable WB afr readings and even if that was possibly a part, I've swapped from left to right and the lean reading stays on the passenger side. I've swapped electronics, injectors and about everything I can think of. The WB is the FAST WB and a separate Innovative WB. The FAST is of course better, but again I've swapped them to each side and the problem stays put physically.

So, in conclusion every logical or first place "chase and replace" have been done, but the imbalance is still there so it must be mechanical (internal)..? Is it ill advised to just adjust the right bank 5% richer to fix this, or am I asking for trouble? All things being equal this setup should push 600-650 RWHP, and so my concern is "band aiding" a problem... I'm the tenacious sort, and so the next thing to try unless I find the problem is purchasing the adjustable cam gears and adjusting them dead on to see if that's it. I also may resort to yanking the damn thing and inspecting the valves and or rings to see if that's a part of the problem, but the leak down or comp test would have justified that which it didn't...

Any suggestions?

 

[Chuck Leeper]

How much leaner?
Are the sensor bungs located the same on both sides, with regard to the turbos?
Same sensor traded side to side?
Seperate cam drives for each head? Chain, or gear?

 

[Spud]

How much leaner?
Are the sensor bungs located the same on both sides, with regard to the turbos?
Same sensor traded side to side?
Seperate cam drives for each head? Chain, or gear?

The bungs are identical on both sides, just downstream from the turbos (I use the waste gates built in to the turbos with an electronic boost controller). The two sensors are the FAST NTK WB that the FAST ECU needs, and the other is a Bosch that the Innovative guage reads. So, one guage (The XD-1) on the dash reads 12.3 while the FAST WB on the dashboard of the computer reads 13.5. I swapped the sensors so the FAST WB was on the driver's side and the Innovative on the passenger side. Then the passenger (Innovative WB) read 13.5 and the FAST WB on the driver's side showed 12.3...

As far as the cam drives, they are driven by chains that run off the crank. The two big chains go up to the exhaust sprocket/cam where a secondary chain runs from to the intake sprocket/cam. I had a professional speed shop degree the cams according to the cam card from Crower and it was all to within 1 degree. So, possibly the 1 degree is enough to make a diff if the intake was off 1 on the passenger side. He never told me which cam was 1 degree off though (without the adjustable cam gears he could only get it to within 1 degree)...

Thanks,

Spud

 

[Craig Smith]

Hmm...

Find two cylinders that fire 360 degrees apart, one on each side of the engine. On the first cylinder, roll the engine until you have .050" lift on the intake valve. Now, roll the engine exactly 360 degrees and check the valve lift on the intake valve of the opposing cylinder. Repeat for the exhaust valves. Unless I am off in my thinking, this should answer any questions you have regarding cam timing. Hope this helps.

 

[Spud]

Thanks for the advice... Before I go tearing it down, I will try testing the opposing cylinders as you've noted. Degreeing the cams is a process I'm not completely conversant with, which is why when I had mine done I took the assembled long block to my local speed shop to have them degree the cams, and so it's entirely possible they didn't do it spot on. It's just that at this point, I have gone through virtually everything on the periphery of the engine and supporting stuff to chase and replace, including wiring the injector harness properly (you gave me that advice previously).

I will probably not get into it too far for another couple weeks until I get it on the actual road... Still tuning in the garage...

Spud

 

[Spud]

Is adding fuel to 1-4 wise, or?

Sorry, I had a brain fart while completing the reply. I was watching the Dallas/Vancouver OT. Great success.., High five!!!

I guess my question is if I'm adding fuel with the ICC on the ECU for the passenger side, is that just masking problems I should really be digging in to determine, or is it small enough to not worry about it? Also, I only have to add 5-6% on cylinders 1-4 (passenger bank on the 4.6) to make the right side match the left. Is that a big deal, or in your opinion how "off" would something internal have to be to cause me to have to add fuel to the tune of about 6%???

I'm trying to determine if the anomaly warrants taking the valve covers and timing cover off to degree the cams properly, or even just the valve covers off to do the 360 degree opposing cylinder test Craig mentioned..?

Do I just run with a tune or does it warrant further mechanical inspection? I'm going for 650 RWHP which isn't too tolerant of mechanical anomalies at those levels...

 

[SloGN]

how do you control the coils using COP coils ? are you using the ford edist box? One wthing i would check is to see if the ignition timing is where it is supposed to be.


lowering the ign timing will make one run lean out as the timing get lower.


also have you veried that what the ign that is set in the fast system is actually what is on the motor using a timing light?

 

[Chuck Leeper]

2 more..

"ideas/questions"..
1. Given you are using internal w/g's, would it be feasible to take a look at exh gas backpressure under the 2 turbos??
The reason I ask is, internal gates, & actuators may have a lower level of sensitivity than the externals. A differential in backpressure could cause flow differences, that in turn cause different EGT'S.. all affecting the A/F rato readings, side to side??
[I think the sensor mfgrs publish info on output differentials, due to pressure and temps..]Craig??

2. A friend has a 10.5 car. We found repeated gasket failures on the dr side. It was determined that the T/B facing that side, caused serious leanout of the dr side cyls.
Does this engine have the air intake on the dr side, blowing into the pass side?

 

[Spud]

To answer the questions from the last two replies, please note:

1. The FAST is set up properly for the dual coil pack setup and Ford EDIS-8 module that I run. So, it's set up as "waste spark" which is what I'd run with the individual COP modules that I can wire-up if I want to, but both are set up through the EDIS module not the FAST Edist.

2. I believe the timing is at around 25-28 degrees around idle according to the laptop dashboard.

3. The intake is a custom sheet metal intake that takes in air from the front of the motor not either side, and so air flow should be identical to either side.

4. How would I measure the backpressure and EGT's properly if I don't have individual EGT sensors..? I could use a infared thermometer I guess and just point it at either header while running..?

I think that answers the questions. What's your guy's opinion on trimming fuel to compensate, or should I tear into the motor or at least take off the valve covers and front timing cover to check the cam degree..? I'm thinking that the cams themselves (billet Crower Stage 2 blower cams) and or maybe how they were degreed might be causing the anomaly on the passenger side, maybe the driver's side is running where it should and the passenger side isn't the problem side just because it shows 1 afr leaner..?

 

[InjectConnect]

Spud
You said you were still garage tuning so I take it that the A/F difference is at idle and low rpms. If this is so I would load the motor a little against the convertor to see if you A/f starts to stabilize many times you can have a header leak as small as a pin hole up stream of the 02 an get a bad reading at idle speeds. Are you assuming it is lean on the entire bank of cylinders, maybe it is just 1 cylinder. Use a heat gun to check the pipes about 2" from the head. Back pressure would be a problem at WOT. This is a start It can be many other things.

 

[Spud]

Spud
You said you were still garage tuning so I take it that the A/F difference is at idle and low rpms. If this is so I would load the motor a little against the convertor to see if you A/f starts to stabilize many times you can have a header leak as small as a pin hole up stream of the 02 an get a bad reading at idle speeds. Are you assuming it is lean on the entire bank of cylinders, maybe it is just 1 cylinder. Use a heat gun to check the pipes about 2" from the head. Back pressure would be a problem at WOT. This is a start It can be many other things.

It is primarily in the garage for the moment. The weather just started to get reasonable, and so soon I can at least take it out for a stretch and do some datalogg runs on some back roads etc... I'll have to get a heat gun if I'm going to take temp readings from the headers. BTW, I am not running cats at all right now. I will get a better heat gun and check the header tubes when it's running, but it's tough to get in there being that it's a DOHC V8 stuffed into an engine compartment fit for a 4 banger! However, if I jack the front up and remove the front tires, I can get a clear shot at the exhaust tubes at least.

Cylinder #3 was showing a little lower in a compression test than its sister cylinders (#1. 155 #2. 160 #3. 145 #4. 155)... I did adjust cylinders one at a time (adjusting #3 up 6% did nothing, and when I went through 1,2 and 4 respectively it didn't bump it up enough). Only the culmination of all 4 cylinders on the passenger side enriched 6% did it. Again, only at idle to about 2,000 RPM but when the RPM goes up or it's under load the margin does definately narrow between the left and right WB. Probably best to get it on the road to see what's happening under load. If the disparody is only at idle I'm a lot less concerned about it. I need to see what the difference is when I'm putting my foot in it, and can review both the FAST and Innovative datalogs perhaps. I'm just looking at possibilities before I'm out driving doing damage...

Spud

 

[Spud]

I took it out last night. I've got bigger problems at the moment. Seems as though the .gct file I had was only good for idle because it drove horribly. The main diff from when I ran last is the custom sheet metal intake, different TB and TB sensor, and the ECU was changed to SEFI, and I've got the injector harness hooked up right now where before it was off. I'll have to put a street-able tune on it somehow or swap back the stock intake for now.