Sentinelist

EDIT: If you're just now joining us, the action picks back up with a resteer at post #81/page 6

This is just to update and re-steer my last thread on this with better focus. Last weekend - when the car was running brilliantly - I decided to apply power to the cruise servo just to see what was up with it after I recharged my K&N air filter (not much oil, cleaned and dried well). I cranked up the engine and the car has a ROUGH idle, and the cruise servo is ticking like mad. Shutdown, disconnected the servo (going to dissect and clean that later to reattempt), recranked and still a rough idle. Repeat without the air filter, rough idle. WTF? I took it for a spin and found the engine itself seemed to be running fine with no misfiring (though I then changed out the spark plugs with new BOSCH Platinum+ anyway and put in a new battery, no real change but it may have taken the edge off, plug wires look good and were recent w/ PO, checked out during the PPI last month, and distributor looks fine but I haven't unbolted it). But there is a consistent buffeting sound from idle all the way to WOT as it's trying to suck air, or it's clogged up somewhere (bad cat?). Nothing got into the airbox while I was cleaning it TMK, but beyond the flap I haven't inspected. Airbox plumbing is clear. I still have 1.8 bar of boost on WOT, so no loss with the turbo system. Vacuum line system was traced, and aside from any holes in the lines that suddenly occurred for some reason, all connections there are secure after following the diagram on the Lindsey Racing site (and eyeing their kit next). Idle is stable, so I don't think it's the ISV. Really slow off the line- bogs down if I really try and make it move.

Did messing with the cruise servo jack with my throttle position sensor? Did cleaning the air filter somehow kill my DME sensor? Does it still sound like the vacuum system regardless? Has this happened to anyone else? I'm digging deep on the search here and am still studying several threads and Clark's but wanted to ping here and see if you guys could help steer me in the right direction. I'm headed to AutoZone to pick up a multimeter to test the DME next...

stew-gart44

When you get low on gas put fuel injector cleaner in it see if it runs better..if so clean them..

stew-gart44

ive had same issue's as you and it runs ruff one second perfect the next im gonna change (i got same plugs as you)plugs and then clean or replace injectors..

Sentinelist

This is consistent, and I ran a bottle of Techron through it last month. It's not low on gas nor do I run it to empty. I don't think it's a fuel issue.

Sentinelist

Any late Sunday evening takes?

TexasRider

What Stew is talking about above is to first run the tank down and then add injector or fuel system cleaner or both plus re-fill tank as per any cleaners you select instructions. If it improves then you can think of sending out your injectors for re-building and balancing.

Any problems of this type can be tough. It can be fuel or electrical in nature. You would need to check the fuel filter, the pump and the FPR. And getting a gauge in the rail can be a bit tricky too. On the electrical of course the plugs, coil, and wires.

I would do the easy stuff first.

I would carefully check the distributor when it is off for cracks etc and get a new Porsche Bosch rotor.

If the car did not come with the KN I would just put in a new regualr element filter too and at the same time just a set of regualr plugs and see if it imporves as well.

As for the leaks you can always get a spray can of carb cleaner etc and mist around a bit on the lines and see if the engine rpms change. At idle or get somebody to rev it a bit. Chock it of course and/or stay off the side - just in case as they say. I would look very carefully at the fuel lines as well.

Then you can start on the TPS or even cracks on the DME board if you dont find something by then.

Hope that helps and good luck.

Sentinelist

Thanks, neighbor- that's what I needed. The fuel lines are good and show no signs of leaks, though original. I'm planning to replace these soon regardless (in this next batch of parts). I may try some carb cleaner around the vacuum lines, and probably a new distributor cap/rotor and wires this week though they're recent and the cap isn't cracked. I had actually started taking the cap off last night, but it was 2:00am when I wearily reached for that bottom bolt and basically said "f-that" and hung up my hat for the night! The K&N came with the car but was pretty dirty (almost black), hence the cleaner/oil recharge. I think the plugs I got are OK, no? All 4 were gapped near-perfect out of the box and aren't very fancy. I'll move to the fuel lines (regardless), filter which I'm really leaning towards at the moment, FPR as well, and fuel pump afterwards failing all that. What about the AFM system? I am quickly turning into a Clark's Garage addict...

I've basically added all these parts to my cart on 944online.com (anywhere better?) and am looking at $515 before shipping for a crapshoot... This may be a long-term piece-by-piece process if the first few parts don't fix this (hopefully this thread will help me whittle down a 'Top 3' consensus, ha). I've already fronted several hundred bucks for new belts and hoses before even picking the car up last month, so I'm still in a slight recovery mode after that and the purchase of the car itself. After the car passed its PPI with some fresh maintenance done and was running like a champ, I was hoping that would stay a champ for awhile. But after a sudden 700 mi. drive home, it's new nearly-daily driver mode has expectedly brought some needs out of the woodwork that weren't there before in its previous 'driven bi-weekly' home. One sign are the interior rattles I am slowly resolving one-by-one as they surface. The car will need a little more sorting under my watch regardless if parts have been replaced 'recently' or not. At least then I'll know they're taken care of, and also the weather has finally cooled here in Texas making garage evenings rather enjoyable with some beer and tunes.

I should have clarified when I did the bottle of Techron last month I actually did pretty much run it to empty- first tank after arriving home from Nashville. I've been filling it up once I hit 25% otherwise.

odurandina

sorry about your misfire. hopefully you'll get it worked out soon.... just a thought about the old 1970 era cars.... there weren't so many lousy musclecar engines as there were bad habits. and the oils back in those days sucked. so if you started with any small block from the big 3, and if you run a mild cam, get a valve job, dump the Rochester carb (if it happens to be an sbc) for a decent holley or edelbrock (or better yet, fuel injection) and run a better ignition, good spark plug wires etc, and finally an h-pipe/x-pipe, resonator and larger magnaflow, and use decent synthetic oil and any muscle car engine would purr like a kitten for years.

our large four cylindar engines on the other hand....

Jfrahm

Check the valve timing and spark timing first, could be a loose distributor rotor or a slipped timing belt. Then run it with one plug lead disconnected at a time to see if it affects mostly one cylinder. Could be a burnt or dropped valve or a bad injector, bad injector wiring...

fwb42

How about a shorting plug wire. Look for sparking when it's dark.

Sentinelist

Good ideas, folks. I'm going to spend some time on those after cleaning the DME sensor tonight- it looks visibly corroded at first glance actually. Also at a glance, the manifold gasket appears to be leaking a teeny bit of oil just around the driver's side around the #4 plug well. That's kinda odd.

I don't think the TB would have slipped- the car on many start and run occassions now is very consistent with this problem and the TB would have shredded or fallen off by now. Situation is abnormal, but stable. Also the TB (and water pump) were just changed last month the week I bought the car. New other belts and upper/lower hoses at that time too. It's been driven 1,000 mi. since that recent work was done. After some heavy research on here and Clark's until 2:00am (again) last night, I'm eyeing the FPR and fuel filter with heavy suspicion but will finish attacking the electricals first. Also will check the AFM sensor and clean that up if necessary- that's actually closest in line to where everything started going wrong all of the sudden (K&N recharged). Going to take out the DME and KLR box for a once-over as well. Hopefully I'll have time this evening. All of this may culminate around the fuel rail, harness and injectors if none of the above works. Car has never stalled or threatened to, so I think the fuel pump is fine. I still haven't counted out the vacuum system. Am I on the right track?

ZR8ED

Might be a stretch here, but I ran some injector cleaner through my DD, and with in a couple of weeks, my o2 sensor crapped out. Car didn't run very nicely. Very odd that it suddenly went one day, and the only thing I had done to the car was add some injector cleaner. It may have coated it, and caused it to give poor/no readings. Car ran flawlessly for months prior. I've always been suspect of adding cleaning chemicals to the gas.

GTSilver944

While this probably isn't the issue, it wouldn't hurt to clean up all the grounds and put some divalent electric grease on them.

TexasRider

I generally dont run any cleaners either but sometimes it works and then sometimes it breaks up some and gums up somewhere else. If you do run some through most pro wrenches tell me to run the car up to red line some to help clear it all through. I think the pro wrenches are about half and half on the cleaners. Some say it works in the right situations. Some say never works.

TexasRider

I thinnk the fuel filter and FPR are right, plus check or replace the easy stuff like the plugs and wires and get the good rotor as I said. Some cars are not so much on the Platinum plugs.

I really would lay that KN aside and just try a regular filter. I have seen enough recharges of dirty filters go bad and cause unusual things.

If you do get a fitting and check the FP and FPR be extra careful of the rail and threads.

As for parts most of mine are Porsche just because. But I do also use Paragon. Top notch guys right here in Texas and I sure will use Jason for my new Konis.

Here are some of the Paragon parts for you to check

http://www.paragon-products.com/Para...arts_s/411.htm


And again I would look at that DME board. A crack or a loose joint there can cause no end of hell. Many can be fixed with some careful re-solder.

Once all of that is known good and/or tested and replaced, and the timing checked, then the most likely spot is the reference sensors. I am sure they are are on Clarks as well. Probably a test method as well. A couple of these will be $500 so thats why I say do the other work first as it may need replacement anyway unless you are very sure of when it was done.