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Slight chugging up hill...

Booba5185

Booba5185

New member
Anyone know how to do this? Ever since I finished my engine swap I've been having a slight chugging feeling going up hill. Basically everything on the engine is new, or has been tested\gone through by me. When I was cleaning everything I painted my supercharger black, and I took the BBV off. I've pretty much narrowed the problem down to a leaking S\C gasket, or the BBV valve not being adjusted properly. I haven't monitored my LTFTs when this is happening, but I did the 1 minute 2500 RPM test and I averaged around -12%, which is rich right? This is why I'm thinking the BBV might not be adjusted correctly...a leaky gasket would would cause a lean condition (positive LTFTS), right? Oh yea, at times I'll get small amount of Kr, something like 1.4* today when I test drove it, not much at all.

Anyways, back to the BBV question. How do you guys set yours? I did a quick search and didn't find much, other than people wanting to squeeze more performance out of the engine and failing (caused KR). I want mine set CORRECTLY, not pushed all the way down or anything like that.
 
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Re: Properly set the BBV

I'm hoping not, but I suppose it possible. The only gasket I reused during the motor swap was the supercharger gasket, but other than this chugging it runs GREAT. I'll get 7.2PSI out of it consistently. As far as the TC problem, is there any way to test it? Do you happen to have a link to a write up on how to do it, or anything of the such?

Thanks for the reply!
 
Re: Properly set the BBV

Courtesy of Dave from TEP's website:

[h=1]TCC rpm oscillation[/h]



Tach bounces up and down a few hundered rpm while cruising in lockup:


Another common problem / concern of this transmission and more pronounced with added engine power or higher mileage. This generally happens when the valve body has excess wear in the TCC regulated apply valve area but also has other causes. Excessive fluid leakage in this area of the valve body causes TCC apply pressure loss and can lead to uncontrollable TCC operation which causes the engine rpm to bounce up and down a bit. This problem is noticed most after driving a while and speeds between 42 and 70mph and in 4th gear.

There are other causes to this problem that can be from a hard and shrunken TCC regulated apply valve end plug o-ring, worn or shrunken teflon seals on the input shaft, a bad o-ring on the input shaft that seals in the torque converter, a faulty torque converter clutch, and even a bad pressure control solenoid.

Another common occurance is a worn out sleeve in the channel plate that supports the input shaft.

A dirty MAF sensor can also have effect on this condition and should also be inspected. In the service field it has been found on occasion that a complete PCM/TCM reflash can also address this problem, though I have found that even if this helps the problem can come back in a short matter of time. Code P0741 may be found in the pcm memory as a stored code and is described as Torque Converter Clutch Stuck Off. When this happens adaptives shifts are disabled, TCC operation is disabled, and 4th gear can be disabled.

Generally a new or reman / repaired valve body will correct this condition and a new EPC solenoid is always suggested as well. The TCC/PWM solenoid is rarely ever at fault for this condition but is also a good idea to replace if you are reparing the transmission. Again the valve body is the common cure BUT not always the culprit and certainly not the whole problem after this has been happening for a while. Any time a torque converter fails there will be debris going back into the trans. There is a pressure relief valve in the channel plate that will collect debris from a bad torque converter and reduce cooler flow, cause trans to run hot, and greatly effect TCC operation and can destroy a new converter in a matter of miles if this isnt carefully inspected or upgraded. The best way to verify proper operation as commanded by the pcm is with a scan tool by viewing TCC slippage rpm, TCC duty cycle, EPC data, and checking any codes and making sure the engine is running properly and a misfire is not a false sense of a torque converter problem or shudder.
 
Re: Properly set the BBV

My RPMs aren't fluctuating enough to show on the tachometer, but it is enough to feel. It happens lower than 42 MPH as well, around town if I go up a hill anywhere from 35-40 it will happen as well. Seems to be worse when more weight (the family) is in the car, so I'm thinking it's engine related. I'll try a new MAF sensor since I have one laying around, then I'll replace the supercharger gasket. Is there any procedure to setting the BBV? I would really like to rule that out as a suspect.
 


Re: Properly set the BBV

BBV adjustment really isn't a thing.

It's not like a wastegate where it makes a big impact on performance.

It really is only there to open under vacuum, and be forced open when the PCM wants to reduce engine power.

I only ever put it on, and lined the holes up and bolted it on. Never really paying much attention to where it was. Only made sure it wasn't preloaded.
 
Re: Properly set the BBV

That's pretty much what I did. I held the end of the plunger to the supercharger case with my thumb, the tightened the BBV bolts. I guess it'll be a new supercharger gasket, I want to upgrade to the newer metal style for my Gen V anyways. What I don't under stand about the gasket solution is the fact that a vacuum leak would cause a lean condition, which would put my LTFT's in the positive, right?

I won't have the car back until Saturday, so I'll try swapping out the MAF then. I've done a fuel pump rewire, and I've also torn the MAF plug apart and soldered the connections. When I bought the car the wires were fraying a bit. I've got extra grounds and a larger charge wire, and while the engine was out (for around 4 months!) I cleaned every sensor's connection, along with every ground, so I think I can rule a connection issue out. It does seem to run a bit hot, it'll max out around 200-225, but this issue doesn't seem to be temperature related.
 
My wife had to drive it on a 600 mile road trip today, and she said it got up to 7.7* Kr, which is double what the highest has been since the engine swap. Tomorrow I'm tearing into it and checking for more vacuum leaks, and I'll see if I can't warranty out my plug wires and plugs. It had the same gas it always has in it, 91 no ethanol.
 
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