Erratic at best

[Danin]

Hello all.
Okay, let's see..where to start. Bought an '87 T-Type, 100k+ on it. ($2,700, bent valve and half the engine was in the trunk.) Had the heads done, stiffer springs (Don't recall exactly which - At the time, a local GN owner was running the show for me.) So we get it put together and running, and I must say, this car blew my mind. I got high 14's, and was pleased at the time. Since then I've done very few mods except a -ton- of chip expiramentation.
Here we are down the road, total modifications done: Hotwired fuel pump, one step 'colder' plugs (Once again, I don't know which they are), ported and rebuilt turbo, throttle body heater bypass, replaced heater core, a custom weak EGR spring workaround (that impressed alot of people, I might add), various electrical modifications (Fan switch, custom in-dash chip thumbwheel, minor things really.) and a minor rear end suspension upgrade.
And now comes the fun part. I'm having performance issues and can't seem to track it down. When I first start the car, it runs and idles great, and if I really put it to the floor, it just GOES, and does it ever want more! After about two minutes of driving, slightly more if I'm nice to it, we start with the problems. After reaching running temp, the idle becomes increasingly rough/searching. At this point, accelerating is okay, best between 0-5psi boost (During vacuum it still bogs somewhat) and over ~5psi I get knock, bucking, backfiring out the intake (To the extent I can feel it through the gas pedal, stock boost guage spikes, etc) and all manner of irritation. MAYBE a mild grey out of the exhaust, but I've never confirmed that. As it warms up more, it gets worse, but that sweet spot between 0-5psi never really seems to go away.
I've checked my compression against several sources including Mitchell and Chilton references, I've verified proper EGR function, I've monitored fuel pressure (Max of 50psi at full boost, when I can get it) and used a scantool to monitor my MAF readings. They -seem- okay. (I say this because I can't really TELL, you know?) I've done and redone TPS, IAC, and TV adjustments. At this point I've got so many different people giving me so many different ideas it's making my head spin, but they're all 'un-GN-initiated' mechanics. IE; never seen a turbo, never worked with DIS, etc. For example, one guy SWEARS it's my base timing. It's still faster than most of what's on the road. Even in this shape, driving it after driving my Mazda for a month blew my mind. BUT.........
PS: YES, I've removed ANY modifications that could even REMOTELY interfere, and gone back to my (verified good) stock chip.

[Keller]

What is your fuel pressure set to (hose off) at idle? What is your max boost? Topping out at 50 PSI sounds a bit low. Base should be set to high 30s-low 40s at least, so your top pressure should probably be higher.

A high 14 stock is what a wheel-spinning TR should do. A 14.6-14.7 should be no problem without headwork.

[Danin]

My fuel pressure with the hose off, I forget and have no current means of testing, though it's using stock injectors and stock pressure regulator, and I do remember testing it compared to a manual for the car, and it was normal.

As for a high 14 stock, that -is- a 14.6 or 14.7, which is what I got before these problems began. Right now I doubt I could clear 18. It's -bad- once it warms up.. I bet right after starting it cold, I could beat 13.7..once again however, no means of testing..

Since my last post, I also investigated and logged some data with DirectScan, and can find -no- oddities whatsoever. MAF line looks clean, which is one of the last things I had left to suspect..

[Keller]

I'd be interested in what the block learn and integrator values look like. Especially since the car starts running like crap once it gets hot enough to be in closed loop. See http://www.gnttype.org/techarea/faq/BLMINT.html for some info on these fields.

Had a local with similar problems. Turns out he had a non-TR MAF on his car anddid not realize it. Once it got into closed loop, the BLM numbers went wacko with no clear reason.

[Danin]

It's actually not an instantaneous change when it crosses over closed loop, really, just degrades swiftly once it starts getting hotter. I've also outright disabled closed loop and it still had about the same issues.. I still have the stock thermostat, it's a 180 I believe? (I really want to get the 160 in there, what's your take on those?) I noticed today that it started to get worse when the MAT started to reach 110 and the engine was in the 190-195 range. At this point I was in heavy traffic and not moving swiftly, and I had my fan hotwired on, but I somewhat assumed this was a normal operating range.. I've actually done some looking at my BLMs and they're not exactly the best.. I have a few down at 109, a few up around 140.. (Footnote, I didn't cross 196, and it only stayed that high for a few seconds at most, so I'm not -grossly- overheating it....)

As for the MAF being from a non-TR vehicle, it's entirely possible, but it ran fine for just under a year and the MAF has not been changed out.. Is there any particular way I could check if it's been changed out prior to my owning the vehicle?

If you'd like my DirectScan information I'd have to re-capture it, the floppy I was using to store the logs (like a moron) decided it was unhappy with its present incarnation and gave up. I could also send you an image of the chip I'm using.. If you'd like to contact me via AIM/ICQ to discuss this further, feel free..contact info is in my profile.

[Danin]

Okay..after a bit more frustration I ripped out the vacuum lines that control all emissions systems..everything non-essential.. Tested the rest. Borrowed a boost line (with a check valve of course) to hold the EGR shut under boost, just to be sure that wasn't the cause. Still had issues, so I called a local GN..he gave me the MAF off a third local GN, and immediately after installing it, my car decided to start falling FLAT on its face after starting, if starting at all. I mean, this thing doesn't even get me to idle - yet his car runs okay with it. His fuel pressure regulator is, no doubt, set ENTIRELY lean because DirectScan shows 40gps flow with the car off, and the number jumps -quite- randomly between 0 and 255. So I had a good laugh. (A -really- good laugh, though I'm not sure why it was so funny - probablly to much caffiene and not enough sleep.)

And we're down to suspecting the fuel pressure regulator, which (after some hard thought) hasn't been tested in alot longer than I thought. It would've been tested tonight (and replaced with a known good, just to see) but -someone- who shall remain nameless forgot the tester and didn't bring the good one. BUT, I can't complain about free.. I just thought I'd update, start some gears spinning somewhere perhaps, because mine seem to have all but stopped.

[Danin]

Yet another update - YAY.... *Sarcasm*

Okay, not the fuel pressure regulator. Threw a known good in, as well as a pressure tester. At idle, pressure looks great..static, vacuum unhooked, we get roughly 38lb..under 5lb boost, 42 or so. Just like with my old regulator...

Another neat thing - I decided to unhook my turbo to see what happens. (Wastegate arm, anyways) It actually runs fine. Mild very minor stumble from a stop, but it gets up and runs all the way to redline before shifting just as hard as it should, all the way up to 90mph or so. ****, it's almost FASTER with the turbo off, because with it ON, I can only reach roughly 25% throttle before the turbo passes the 5lb sweet spot I'm stuck with. I'm at a loss.. Starting from square one again tomorrow....

[GNetic86]

I'm going to take a wild guess and ask if you changed your coolant temp sensor? I'm working on a simliar problem to yours, but the opposite. My car runs like crap when cold but smooths out when it warms up. I was thinking about doing the coolant sensor on mine to see what happens, but I just found a vacuum leak in the climate control system that may have been causing issues so I'm working on that at the moment.

--jeff
86 GN (stock)

[Keller]

Originally Posted by Danin

...so I called a local GN..he gave me the MAF off a third local GN, and immediately after installing it, my car decided to start falling FLAT on its face after starting, if starting at all. I mean, this thing doesn't even get me to idle - yet his car runs okay with it. His fuel pressure regulator is, no doubt, set ENTIRELY lean because DirectScan shows 40gps flow with the car off, and the number jumps -quite- randomly between 0 and 255...

Are you saying his MAF numbers jump around like that? And this MAF causes your car to not run? I would verify that its the right MAF, and that its installed right. i.e. Pointed the right direction. I've heard of people doing an "oops" and installing one 'backwards' and not figuring it out right away...

MAFs should not be reading 40 g/s at idle.

[Danin]

GNetic86 - I haven't checked that, but according to the readings my computer is taking compared to the day, traffic, etc, it seems to be fairly accurate - though I will certainly keep that in mind. Thanks for your input.

Keller - Yes, his MAF numbers jump around. No, it's not installed the wrong direction, and it is the right MAF. And, it's not reading 40g/s at idle, it's running 40g/s engine OFF. I probablly should've directly mentioned that we decided that MAF was bad, and replaced it, and his car ran -much- better...after he turned his fuel pressure up to a normal level. (I also came to found out they were trying to burn a new chip for it and having issues with idle and mid-load. Gee, I wonder why that might be.)

And here we go again with the long post.. Sorry, but I'm running dry at this point.

And on a new note, I'm about to give up. Monday, I reworked the entire fueling and air intake system, new hoses, checked and double-checked everything. New plugs, new wires. Fresh oil change, old oil looked okay. Coolant looks fine.. I even pulled head covers to check rocker arm movement, and it honestly appears to be working just great. Injectors are clean and maintain a correct spray pattern..we found one bad hose, Turbo to Intercooler, replaced it and it didn't help much - I now have a new Intercooler (not really new, known good used though) in my trunk awaiting free time and motivation, which I'm running short on. What's the word on crank sensor failure? Perhaps it's running alright by pure tolerances, and my fault is only showing under load? Another note, I did notice the inside of my pipe from the intercooler to the throttle body appears flame-licked; black sooty remains, but powdery..not like the oil I had before I replaced my turbo with a ported rebuilt..but that doesn't surprise me, I knew it was backfiring out intake.. (Can feel in gas pedal and my boost guage spikes pretty good.) What I don't know is why.
And the best part? I can't even think of anything else to -ing check! DIS module, but that really shouldn't only mess up with boost. (As mentioned before, upon removing turbo wastegate arm, the car seems to run perfectly normally, idle to redline and back while driving...)