Ok this is going to be a little hard to describe but I will do my best. First, its an 85 TC with the mods in the signature list. I am running a Forge BOV (FMDV004)with the Red spring (23-30) tried the yellow too. No change. Running 42psi fuel pressure.
Ok I can run at WOT 1st thru 3rd with the boost pressure maintaining a solid 20 PSI with no issues. When i shift into 4th, the boost is slow to build and it actually seems as if the waste gate is opening, I get a bucking sensation and boost fluctuates. It will not smoothly build boost up to my max. Now if I let off the throttle, staying in 4th and then floor it again it will build up to 20 without a hitch. It is a little frustrating, any Ideas would be great.
I have cleaned the gillis valve thinking that had something to do with it, but it didnt.
I'd try removing the bov temporarily and see if the problem goes away.
Nah I think I am leaning out, but I need to get a Wideband and do some datalogging.
I checked your cardomain page and didn't see answers to these:
Do you have the knock sensor disconnected?
Is 42psi base pressure?
Do you have a fuel pressure gauge?
Injector size still 35 lb/hr?
What does the A/F meter say?
+1 on the BOV.
Knock Sensor is disconnected. Base Timing at 12 degrees spout out.
I had set base pressure with vacuum line off at 42psi and later moved it up to 45psi, resulted in no change.
I do have a fuel pressure gauge (SW electrical). Also used a portable one to set FP in the garage.
I am still running stock 35lbs injectors flowed and matched.
Also I only have a Narrow Band A/F meter, but i does show lean when it bucks. Granted that means nothing. I am looking into purchasing the Innovate LM-1.
I have not yet tried removing the BOV, I would however like to go to a Bypass Valve. I just have not yet come up with a suitable method to accomplish this yet.
A bypass would be better since you've got a VAM. You might check to see if the wastegate is functioning properly. Is your FP changing under boost?
Going lean leads to knocking, burned pistons, destroyed plugs, blown HGs and worse, but I don't think it causes what you're describing.
Well I am still working on this issue, and I have not been able to get this thing to run right. I have turned down the boost back to 10PSI, set fuel pressure at 39 psi, removed the BOV, tried a BPV, put in Motorcraft Ignition parts TFI, PIP and I still have an issue.
The one strange thing I cant understand is this.... I completely took out the VAM (after trying a differant one) and the problem went away.
I MEAN I RAN PERFECTLY WITHOUT A VAM ???????
How can this be ???? I have an LA3 that was reconditioned, could something be done to this that I am not aware of? Maybe a hidden MS inside. I dont know.
Any Ideas as to why Please enlighten me !!
got a different vam?
does it have this problem at 10 psi in 4th or is it only higher boost related?
It does it at any boost pressure, and I have tried another VAM. My friend owns a repair shop and we hooked up every kind of new fangled and old fangled electronic do dads to it, to try and figure this thing out.
Though it still runs like a scalded dog, I guess maybe I have to live with this or do what you did and drop in a GM motor....
Never had this much trouble with my Camaros Geez !
I'm not an EEC expert so somebody step in if there's some bad info here.
It sounds like the limp-home mode kicked in, which means it's running open loop. It it's running well in open loop, then you're at the limit of the fuel system, which means that you need bigger injectors.
What does it do in 5th?
Does it do the same in 4th regardless of whether you ease into it or tromp on it?
It will also do it in 5th gear and if I drive it easy, or lets just say like a sane person it does not do it. It really only happens at WOT in both 4th and 5th.
It actually runs fairly smooth if you just use normal day to day driving. But if lets say your on the highway and you need to pass someone and you floor it in either 4th or 5th it will do the "chug".
Plus i seem to still be blowing 2psi into the crankcase causing oil to come out the dipstick tube. (on my third Motorcraft pcv, have VC vented thru turbo inlet) I am just thinking that may be a clogged oil seperator, but then again I dunno. ?????????
Layla did the exact same thing...
Guy I sold it to pulled the motor for more mods and found a broken top ring...
Ah I do not want to pull this motor out again, and I do feel that a broken ring is not the problem. I only have 700 miles on this newly rebuilt motor. But if after all is exhausted and done I may have to go back in and take a look. Hopefully I will not have to.
Just saying. Mine worked great for 10,000 miles then it suddenly started acting exactly like this, that's the only problem that was found.
Good luck.