It's alive, but not happy

[gsellstr]

Ok, finally got the 531 and IPD turbo cam installed on the 90 745T. Pulls around 10-11" of vacuum at idle, very unstable idle, sounds like it's laboring. The head has 37.5 exhaust valves and mild intake tract porting, fully rebuilt/checked, clearance at .013" cold. Also the car seems to have a rich bog til around 2800 when it wakes up and pulls like it should. The cam is currently running straight up since my cam gear is now a paperweight (hooray for first-gen IPD gear and 40k miles).

Anybody have any thoughts? I've already checked for vacuum leaks, car was running fine beforehand, no other work was done, timing marks all line up.

Thanks!

 

[thelostartof]

how sure are you that the timing is right? it really sounds like the cam timing is off

i know with my V16 i went from like 18" vac to 13" @ idle(from a V15 to V16 and also A cam to V16) but that was from a wee bit more wild of a cam so

the fact that the cam feels like it comes on late is just how the cam works, tho if cam timing is that low something else has to be off. do a leakdown test and all that jazz

 

[gsellstr]

I don't have the stuff to do a leakdown, but I KNOW the motor's getting tired (hence the sourcing of parts for a fresh build on a squirter block ).

I'm going to pull the crank pulley again tonight, but last time I checked it was still all correct. I was kinda thinking cam timing sounds off as well, but dangit, it all lines up! Wish I had my adjustable gear.

 

[thelostartof]

do you have an air compressor? or a tank?? that is all you need to do a leak down ... $13 worth of fittings from harbor freight and you are done

 

[benflynn]

i busted a cam pin, still ran but not well at all

 

[gsellstr]

Cam pin's good. Brand spankin new with the new cam. The pin's still good on the crank gear as well.

I DO in fact have air, but the measurement of leakage is what I'm not sure of. Last time I did one was at the local JC about 10 years ago where they actually had the specific stuff to do it.

 

[Hank Scorpio]

sounds like its 1 tooth retarded to me. iPd turbo cam should pull way more vac at an idle than that.

 

[thelostartof]

sounds like its 1 tooth retarded to me. iPd turbo cam should pull way more vac at an idle than that.

the IPD turbo/V15 should pull around 17-18min @ idle so

 

[gsellstr]

That's kinda what I thought as well. Justin has around 18 in his 242 but only around 14 in his 780. I will be checking the cam timing again tonight.

 

[gsellstr]

Ok, so I just checked (still have the top cover off). With the cam lined up the balancer shows 0 degrees and the notch on the plate lines up with the mark on the housing. I had a second set of eyes look at it and it appears to be lined up and not a tooth off. I may try and swap to the stock ECU and 4-bar and see how it runs with that setup. It's kinda had the bog for a long time, but not NEARLY as bad as it is now. It's always had at least 18" at idle though.

 

[gsellstr]

Ok, so here's an update. I swapped the stock ECU back in in place of the chipped ECU. The bog is SUBSTANTIALLY less, and still no pinging even at 18psi spikes. Swapped the AMM with a spare I had along with putting my 4-bar FPR back in and the bog is nearly completely gone and the car pulls HARD from about 2800 on. It occasionally stumbles though since I swapped ECU's when it's a WOT in boost, at various RPM ranges (3000, 4000, 4500 so far). Feels like it's hitting a boost cut, but I don't remember that being taken out in the chipped ECU's from Fred.

The idle is still pretty low, and it's only getting 10-12" at idle. Cruise it's still sitting at 8-10" like it was before I swapped the head. I've also got the EGR port plugged so that's not an issue, and the CEL hasn't come on so far either. Cam timing has been verified to be correct.

Any suggestions for the low idle, low vacuum, or random stumble/boost cut?

 

[JohnLane]

Give it another .003" of clearance for the valves and see how it likes it.

 

[benflynn]

Give it another .003" of clearance for the valves and see how it likes it.

i just said to hell w/the silancers, opended it back up nicely

 

[gsellstr]

I think first thing I'm going to do is verify it's just an issue with the cam causing issues. The motor is going to get swapped out later this year, so I may throw the turbo cam back in there. For now though if the VX makes a difference and allows the car to run decent I'll run with that.

 

[MikeHardy]

i just said to hell w/the silencers, opened it back up nicely

clearances should be set with the silencers removed anyway. personally i removed them on all cars i've set and left them out. not been tappety

 

[dl242gt]

bog

My engine pulled low vacuum until I adjusted the valve lash. It also needed the cam timing advanced because the head was machined to make it flat. If your head was machined even a little bit to make the surface flat. You'll need to advance the cam timing about a couple of degrees to account for that.

 

[gsellstr]

Hmm, strange, my last post didn't stick. Anyway, here's an update.

Compression is 150-160 across the board
With 40psi supply I've got between 4-7psi of leakage on a leakdown.
ECT is within spec
AMM resistance checks out or 2 different AMM's for the load side, but the heater resistance is WAY off on both. Both around between 20-22k and spec is 2-3k. Strange.
I bumped the cam 1 tooth advanced and the idle and vacuum didn't change but the performance did get much worse on a road test.

Next up in a few minutes is a swap back to the VX and see what that reveals.

 

[gsellstr]

Ok, here's the latest.

I installed the VX with .014" lash. Vacuum went up to around 15" at idle. Pulls MUCH harder than the turbo cam. Still surges at idle, still has the rich bog, though not really bad. Swapped back in the chipped ECU and 3-bar FPR. We'll see what that does tomorrow.

Odd thing I noticed on the last drive with the stock ECU and 4-bar. While under boost you can hear air being sucked in til about 12psi, at which point that noise goes away completely.

 

[RvolvoR]

Ok, here's the latest.

I installed the VX with .014" lash. Vacuum went up to around 15" at idle. Pulls MUCH harder than the turbo cam. Still surges at idle, still has the rich bog, though not really bad. Swapped back in the chipped ECU and 3-bar FPR. We'll see what that does tomorrow.

Odd thing I noticed on the last drive with the stock ECU and 4-bar. While under boost you can hear air being sucked in til about 12psi, at which point that noise goes away completely.

hmm, sounds like youve got a leak somewhere

 

[TurboBrickMan]

Any update? (kyle-klr142 on TBM's comp still at Doug's)