NCLA951

Is it the emissions valve that is connected to the fuel vapor lines? My diaphragm was broken and was putting vacuum on the gas take, and also of course boost. If you can hear it hissing replace it, it's an easy thing to eliminate.

bradthebold

Yes, it looks like it's this fuel tank breather valve. http://www.pelicanparts.com/cgi-bin/...928+110+429+08

Pressure testing, it buzzes at low pressure and sounds like it's just letting all the air through >10psi, much more than a hiss. This was going to be my next step, thanks.

bradthebold

So I have fixed and replaced a bunch of things and it runs almost identically. It doesn't die when letting up now, but it still drops drops RPM and stumbles around 1800RPM. Vacuum doesn't seem to have improved :10-12in cold, 15-16in warm. 18+in after tripping the TPS <1k RPM though.

FQS is set at +3%. It runs worse and idles lean when at 0.
Piggyback is not installed; shorting plug is in.
I measured fuel pressure: at idle it flutters between 2.5-2.8 bar. When shut off it sits at 2.9bar and was about 2.8bar after sitting 20 mins.
MAF signal voltage is the same on the MAF and DME side.
Vacuum leaks: I replaced the leaking fuel vapor valve, a leaking thermovalve, jb welded the ISV, epoxied the IM connections. The DV leaks a little under full pressure, but it's metered air (replacement on the way) otherwise it is silent now, no leaks.
I replaced the DME temp and 02 sensor. Took the TPS apart and cleaned it, though there wasn't much in there and it looked good. Cleaned and tested ISV with a 9V battery, vibrates with key on.


^ Partially warm after driving around the neighborhood. 18in vacuum after giving it a little gas to trip the TPS and goes rich. Degree of stumbling at 1800RPM varies. It's pretty good here, was worse and setting off the knock light before. Any gas was setting off the knock light before it warmed up. It is rich under light throttle (mid to upper 13 AFR), lean cruising. Even at 0 FQS its rich under light acceleration.

I don't know what to do now unless the TPS is bad. Or is that fuel pressure too low?



Then a separate big issue is I still have no power steering. At some point it worked for a few blocks, then stopped again. First I blew out the cooler/return and feed lines. Then it didn't work or stopped again so I took the pump out to check and the only thing I could find is that hourglass shaped gasket was bulged into the opening towards the center it sits over. I repositioned it and tried to put it back together without distorting it.



I rebuild the pump and replaced the rack with a rebuilt one. There is zero power and it's creaky sounding and feeling when turning. No loud whining. I've bled a lot, fast and hard. It sucks fluid in.

bradthebold

Looks like fuel pressure should be lower with the vacuum line connected at idle, so that should be ok. The only other thing I can imagine is the TPS. I tried to order one, but I can't get the generic brand one anywhere, only the ~$280 Bosch one online or a used one from Lart. Does anyone have a good working one I could test before I have to order one to see if it makes a difference?

Not sure about power steering. Can't get a hold of Travis to ask. Could the rack not work somehow if it doesn't leak, or is it most likely the pump? I might have to get another kit and rebuild it again.

ealoken

i have a oem tps, Can ship from Norway.

bradthebold

Thanks for the offer. A quick UPS price check looked like it might cost more than it's worth to ship it back and forth though.

I just rechecked and it tests completely fine. 5 VDC at the plug, microswitch works at the DME, and resistance is smooth with no flat spots checking the throttle range at the KLR plug. Could it possibly be the problem? I'm pretty sure if I spent the money for a new one it wouldn't make a difference.


As for the power steering, I got a hold of Travis and he thought the feed line might have delaminated and is internally collapsing and choking off the pump. So I'll get a new line and see if that helps at least.

Humboldtgrin

Did you use a digital or analog ohm meter?

ealoken

My 951 will never use the oem TPS again So if needed, you can get it cheap.

bradthebold

I used a cheap digital one. I went very slow and figuring it would jump to 1 or 0 if there was a flat spot.

Humboldtgrin

So you know you should only use an anolog ohm meter to check a TPS regardless of how slow you rotate the potentiometer right? Even better would be an oscilloscope to test the TPS with.

https://www.ebay.com/itm/253102742539

This would be a better ohm meter to use IMO.
https://www.ebay.com/itm/112194582783

bradthebold

Nope, didn't know. I'll order an analog meter and see.

bradthebold

Retested with the analog meter and got the same results. Smooth, in-spec resistance with no flat spots.

bradthebold

I drove it with the TPS unplugged. Idle vacuum was much better, though it idles at 500-600RPM. Even at 600RPM, I was getting 16-17in vacuum. Turned the FQS back to zero and it warm idles at 14.7AFR but is rich under slight-moderate acceleration and cruising - upper 13s. It still stumbles at 1600-1800RPM whether holding it there or passing through it while accelerating. Going 25mph in 3rd just continually bucks. Any ideas?


On a possibly related note, does this 3 pin connector plug into anything? I couldn't find anything in the wire harness to connect it to under the glove box. Also, my 8 pin connector (and most connectors/bolts on the interior) was heavily corroded, difficult to get apart and hard to fully seat again. I zip tied it tight, but the boost gauge and tach occasionally go out until I wiggle it. Can I just replace it with a generic 8-pin connector?

bradthebold

Still no luck, I didn't get to drive it at all last year.

I was able to fix the power steering and the weird stumbling around 1800rpm went away for no reason when I started it this year. I drove it around and it would die when I would let up on the gas - dipping too low rpm and being unable to recover. Then being hard to start without holding the accelerator down. Looking into that, the 1800rpm stumble came back today after a week of being gone.

Everything is pretty much the same as it was. I pressure tested again at 18psi and the ISV is slightly leaking, but I don't think I can make it better. I've pulled it 3 times to jb weld and epoxy it. You can't hear it, but I found it when I sprayed everything down. It barely runs any better or has more idle vacuum than when half the engine leaked.

I tested the TPS again and it tests completely fine according to clark's garage.

I tried to set the idle according to Lindsey with the ISV jumped.

With the TPS unplugged, it runs smoother and I can turn the idle up >1000 rpm if I want. But now that stumble is back. The AFR and knock light don't like giving it gas though. Just revving it normally trips the knock light and makes the AFR go lean. The stumble goes lean too. But, it doesn't drop below idle when I let up.


With the TPS plugged in, it's a rougher idle and I can't really adjust the idle much. Unscrewing the idle screw won't idle >900rpm. I'm tempted to replace the TPS, but I don't think it will help and that stumble is back even with it unplugged.



Earlier this week, before the stumble came back, the car drove fine seeming except for dying when letting up on the gas. It was smooth and I thought I'd almost fixed it finally.

bradthebold

Well, I just went out again and tested without the jumper and the stumble is gone. I don't know if it's related or coincidence, but I know I didn't leave the jumper in all last year when I was testing

At 1/2 turn idle with TPS. Hard to see AFR on outside, but still lean. It takes a long time to fully recover back to idle after dipping.


With 2 turns on the idle screw. It still drops lower and sounds stumbling, but it does it at a higher rpm at least and doesn't try to die. First part is just pushing enough to trip the TPS.