It seems that when I have switched back and forth between the stock throttle body and the Arrington 90mm there are substantial changes to the engine. First of all the throttle response and acceleration is greater with the Arrington, however the idle is smooth as silk and no surging with the stock unit. My question is what table or adjustment must be made to; 1. Get the idle to smooth out a bit more. Especially as you slow down the engine wont "buck". It seems at times it "bucks" back and forth causing the exhaust system or driveline to shock. 2.Get the cold start to idle 200-300rpm lower at initial start and less time in that mode. The engine will surge and lay over until it is out of "cold start" mode. THANKS!
I wish I had one along with your other mods to have this dilemna lol. Hope you get it figured out. You still owe me a freakin test drive you mo fo!
My arrington works flawlessly for my normal driving. Only issue I have is when I drive on the highway for 50 miles or more and then transition to slow speeds or a stop. Then I occasionally get the surging you describe. I forget its an issue because I rarely do any highway driving. I know my tuner has a log of what you speak of and Ill let you know what he says about it.
So far everything I have seen leads me to believe that these TBs will require custom tuning, have you had the set up dialed in yet with a CMR dealer? Thanks Mike
Yes! DynoSteve tuned it beautifully for part throttle and wot. I believe the idle tables and cold start are factory, although he resolved the the cold start idle surging and hunting on initial start up. The cold start surging and laying over while driving away tells me its actually lean?? In the day when I was tuning big inch fuel injected Harleys, we had tables for larger throttle bodies and injector sizing. Once a larger throttle body and larger Weber injectors were installed, one could lean or richen or change the injector pulse rate. We could also based on outside temperature change the cold start rpm and duration of the cold start mode. Also, I owned an modified 2006 Jeep and now have the 2008. Why does the 2008 idle so high at initial start up even when it is already at operating temperatures. It did this also when new and others who own the 2008 have the same complaint. If I swap back to the factory throttle body the drama all goes away......but so does the performance. Thanks, Mike. Steve
I also have that "surging." Slowing from any speed, even gradually, usually yields a chugging or surging. My car was tuned at PPP, but I wasn't sure what was causing the issue. It almost felt like my converter was undecided about downshifting or locking/unlocking. I never thought about the 90mm TB.
Exactly...as I slow down it surges and causes my exhaust to bang around. I was worried that the drivtrain was being shocked and banging. I bgan to think it was my converter/tranny as well. Does your surge/layover when in warm up mode while driving?
Steve, Mine doesn't sound that bad, but it has been there since the moment I drove away from PPP. It is somewhere between a nuisance and a distraction. I was hoping the car was still learning somethingortheother about downshifting and that it was due to the PI2800 TC. I notice it most when the car is warm and the increased idle due to warmup or whatever is no longer there. I have my idle set at 700 RPM and that's where it sits in gear at stop. When I am cruising along at 35 or whatever and see a stop light and simply let off of the gas and brake lightly or even coast, the car does fine for about 2 seconds...enough time to watch A/F gauge go high, low, then spike to 20+ or whatever...you get the idea....then the car chugs or surges as I come to a stop. I thought it was the TC/tranny trying to decide to lock/unlock or downshift. Now that you mention this about the 90mm TB, it DEFINITELY coincides with whatever goes on at zero throttle.
Another thing that is probably not related but may be what you are talking about, but it is actually hard sometimes to tell if my car actually shifted or what gear I am in as I leave from a stop while in warm-up mode or whatever. The trans seems "vague" for lack of a better word and my engine RPM's vary some and act like the car may have shifted to second, then right after the RPM's raise, then kind of bogs. Until I get to 25 or 30 MPH I have a hard time telling what gear I am in. I have gotten used to using autostick until I get cruising to get over the "vague" area. This is MUCH more pronounced when I first start up the car cold. This is ALL in "super-easy" throttle applications. Any kind of mashing of the pedal and I have instant response.
That's got to be a clue. There is a deceleration mode where the PCM will turn off the injectors. Input is a closed throttle input from the TPS accompanied by a sharp decrease in manifold pressure. I wonder if your TPS is not sending a constant closed throttle signal and instead an on/off, on/off intermittent type of thing. The engine could be going in and out of deceleration mode (the injectors would be turned off, then on, then off...). It's very noticeable when the injectors are turned off when decelerating or coasting. Just a thought. If you can log your AFR you could check this (might not be able to see it very well visually with all the a/f bouncing around in closed loop mode). Should see it bouncing back and forth with the surging. 20 (or whatever your wideband pegs at) with the injectors off and then back to between 14 and 15.5 with the injectors on.
This sounds very close to what may be happening. Let's say I am in "D" at 35 mph. I let off the throttle completely to come to a gradual stop. With my stock engine, I used to be able to BARELY detect the car as it downshifted once or maybe twice as I was almost stopped. Smooth all the way. Now, after the 90mm TB: Initially after zero throttle, not much sensation but I see the A/F go high, low, then I get the feeling the car downshifted to 2nd and FEEL the car decelerate much harder than it used to...like letting out a clutch on a manual trans. The A/F says blinking 20 (maxed) and then on comes the surging all the way until I come to a complete stop. I will watch the A/F gauge during the surging but I think it stays at the blinking 20 until I am stopped. I will take a video as it is recreatable 100% of the time. I am not sure if this is what sgtstanko has going on also but it sounds like his is much more aggressive.
If I'm on the freeway and then maybe slow down pretty aggressively (brakes) for an exit or something and then just coast you can feel the deceleration mode. The engine brake with the injectors off is very noticeable. Then after coasting (actually still noticeably slowing down) for a short time with no gas pedal you can feel the injectors turn back on. This is also very noticeable. It's like you released the emergency brake or something. Comes very close to feeling like it changed gears. Both during the braking and then when it "releases". If it was to surge on and off I could imagine it almost feeling violent. Sarge might have a bit more brake hp than most (compression). What kind of gauge display do you have? A needle might not show it. Might be hard to see even with a digital display. It's going to be bouncing around in normal closed loop mode between 14.something and 15.something to start with and then seeing if it bounces up to 20 for a while might be difficult. From what you described it looks like when you first get off the throttle it goes to normal closed loop and then goes to deceleration mode (when you see it go to 20) and then it starts surging. How fast is the surging? If it's close to once a second or slower it shouldn't be a problem to see it on the gauge. If it's a couple of times a second or faster then it might be difficult. Logging would show it for sure with any decent gauge. Oh, hey. If you have a DashHawk or Predator you could also log the Throttle Position Sensor voltage and see what that looks like while it's happening. I believe you should be able to log the MAP sensor as well. If it's the throttle it could be just the signal fluctuating or it could be the signal fluctuating because the throttle is actually moving. So if you see the TPS voltage fluctuating and the MAP doesn't change with it then it's just the signal. If the MAP changes with the TPS signal then the throttle is moving. Either way it might be dropping you in and out of deceleration mode which would turn the injectors off and on. (I'm guessing the throttle is waffling and it's so damned big it's causing an abrupt enough change in MAP to toggle deceleration mode).
Innovate. The surging is not fast...something like every second or more...not rapid. I am going to look into this in the next few days...working my last graveyard tonight. Wife-willing, I should be intoxicated enough after work in the morning tomorrow that I should be able to answer everyone's question about anything. Seriously, I will log some data and I have a feeling I will see data cooresponding with the surging as I decelerate. sgtstanko's post has really got me thinking now...
There are two different issues I think that are getting mixed together. One, during deceleration, 100% converter lock up will net the engine breaking discription I see listed along with the lean condition. After your speed/RPM has reduced below that threshold (full lock-up), is when you see you AF's try to get back to stoich. That's that odd surge you feel sometimes and also one of the times when you'll see the wild AF swings. But the main problem are the air flow tables. These larger or modified TB's are very tricky to tune. Mike at Inertia and I have spend countless hours playing with them with my duals. There is a trick and I can say in all honesty, I don't think anyone understands the airflow tables better then Mike.
I had the exhaust modified and the banging is gone but it does say that the engine is in fact bucking or suging as it comes to a stop. I have noticed the same thing from my A/F. Bottom line this is a case where the part came out and the tuning has not caught up.
I don't understand. More explanation please. I can understand the deceleration difference if the torque converter goes from locked up to not. But the PCM controls that right? And I would expect it to keep the TC locked up when it's in deceleration mode. Sure the a/f is going to bounce around in closed loop mode but there's going to be a very large difference in engine brake horsepower between closed throttle injectors on (hunting for stoich) and closed throttle injectors off right? With the throttle closed but the injectors on the engine is only going to provide some small amount of brake hp. Especially since it's not going to be in the upper rpm ranges (assuming you're in automatic). With the injectors off there's going to be significant engine brake hp from a 6.1L 10:1 compression engine. There might be some sizeable swings in a/f in closed loop mode but I believe the 20+ a/f is only going to be seen when the injectors are turned off.
Actually the TCM controls the torque converter...but who cares. Anyway with the TCM inputs for the torque converter lockup being: * Shift lever position * Current gear range * Transmission fluid temperature * Engine coolant temperature * Input speed * Throttle angle * Engine speed Do you think it is an "unrealistic" throttle angle on decel. that could be causing the problem? I agree when on decel., my 20+ A/F is telling me that the injectors are turned off. Very interesting stuff. Bill
