Chuck Henry

I'm slowly working the car to solid running. I swapped in the LR dual-port this week and a few other things and it's the best it's ever been and the joy meter has bumped up a couple pegs. I was disappointed that one of the new studs broke off with very little force on hand tools (had the stock one off/on many times without issue) and it didn't come with the air fittings you need. But otherwise it seems like a solid product.

So my next two things to tackle are:

#1 Runs Poorly When Cold
Pretty self explanatory I guess. To be more specific, if I start it up and let it idle it's just fine, but really hates to come off idle and you have to slip the clutch keeping the revs up around 3k to make it move once you get it to rev up. All that goes away pretty much as soon as it's warmed up with it getting better as the temps rise but not right until it's at operating temps. Is the idle control valve the most likely culprit? Anything else related to cold running that would be good to check?

#2 Surges/Cuts Out Under Moderate Loads
The car runs pretty much perfect when warmed up and under around 5 psi/50% throttle. When I go up a hill and I have to give it more throttle it starts to cut out. This is often accompanied by a clicking sound I believe to be the wastegate closing. Sometimes only once, sometimes a few times in close succession (1/2 second intervals) with each click followed by it running and lurching forward. I believed it to be the wastegate so I replaced it with the LR one but it didn't really change. What DID change is that I was able to actually control the boost better (had the MBC before on the stock wastegate) and I noticed as I turned the boost up it ran much better in WOT conditions. I've got it at 15 psi right now as I'm testing and I know that's a lot, but if I hit a hill at say 65 mph in 5th and it starts to cut out, I can drop to third and after about a second it clears up and takes off. One thing to take note of, here in Denver we are at around 6,000' and the air is pretty thin. On my Audi S4 turbo I needed way less injector than others at similar boost levels around the country. So I expect that the stock injectors are up to the task over stock boost levels. (what is stock?) I read that it has an altitude sensor and my suspicion is it's not working and it it's running rich under boost conditions which only goes away when at higher boost levels. It's still doggy at 10 psi but better. I know I really need a wide band O2 and I plan to get one before diving into tuning, but was wondering if these symptoms rang a bell for anyone.

Also, a huge THANK YOU for all the help I've received so far. The car puts a huge grin on my face and I now have over 2,000 miles on it since I bought it a couple months ago to have it towed to the house. I can't wait to have all of the mechanical stuff sorted and work on making it look good, but I really don't care how bad it looks when it's so much fun to drive. So glad I saved it from being parted!

Spidey944

When you have a cold start, the engine is in fuel enrichment mode to aid in warm up, etc. Then the O2 sensor comes into play after <2 minutes of running. If you know your O2 sensor is old, maybe start with that.

Also when it's cold outside, seals and such will shrink down a bit, this can cause an unmetered vacuum leak. So check your intake manifold gaskets, throttle body seals, vacuum lines etc. If you can get your hands on a smoke machine, they are priceless in finding vacuum leaks.

Chuck Henry

Thanks for the tip, I think an O2 sensor could be a good place to start for both problems.

Tom M'Guinn

Just some random thoughts (all assuming you have stock engine management?):

I'd check the DME temp sensor to make sure it's not lying about the temp. Clarks-garage has the procedure and specs.

In Denver, you might check the altitude sensor tuck up high behind the glove box. It's an on/off switch (canister looking thing) that tells the DME when the car is at altitude. You can pull the plug off and short the pins to put the car in altitude mode.

http://www.the944.com/altitude.htm


Check vacuum at idle when warm, and check for vacuum leaks.

idle control valve "probably" isn't the cause of your poor cold idle, but not impossible.

Have you set the base idle? See clarks-garage...

Cutting out under load is very frequently caused by poor ignition. How are your ignition parts - cap, rotor, WIRES, and plugs? If condition is unknown, I'd change them. Any chance that clicking is spark arcing from bad wires?



Check o2 sensor as suggested.

Always worth checking the AFM and TPS signals as well. Clarks has that too...

Chuck Henry

Tom,

Thanks, I love a list like that to check. I'll try them all. I've replaced in the short time I've had it:

Coil
Wires
Plugs
Cap
Rotor
Fuel Pump
DME Relay
Fuel Filter
Speed sensor
All vacuum lines
Timing Belts
Fuel Lines
Resoldered the DME
I'll put in a new O2 next week
More that isn't related...

It's all stock except
LR Dual-Port Wastegate
MBC
Venturi Delete

I did notice based on Doug's post that if I let it idle for 2 minutes it drives much better. Still stumbles, but well worth the 2 minute wait. I also have noticed on really long drives (over 1 hour) that it becomes really finicky about on/off boost conditions. If I go WOT and then return to cruising the engine pretty much turns off and will start running after coasting in gear for a bit but is really reluctant to make power until driven lightly for a while. I'm still leaning towards a rich condition, but it could be other things.

Thanks for the list of things to try, that's the kind of stuff I like.

Tom M'Guinn

I might check the AFM, TPS and altitude sensor first based on that list. And of course vacuum leaks -- how much vacuum do you have at idle? You may have two different things going on too -- one affecting cold idle and one affecting the car under load when warm, but both could be explained by an AFM sending incorrect air flow voltages. A wideband with logging (zeitronix) would be a good long term investment and might provide valuable insights. When you resoldered the DME, did you also check/solder the KLR? Had a friend with a bad solder joint in the KLR and it caused the car to randomly run off the WOT maps, with predictable whacky results...

Chuck Henry

I'm showing 14 lbs of vacuum at idle, but I know on the highway I see 16 lbs.

I did the DME because the car was periodically shutting off, I was taking the "if it ain't broke" path with the KLR, but I'll keep that in mind as a possibility.

I'll definitely get a WB, I was wanting to hold of until I got an exhaust and get the bung installed then to avoid doing it twice.

I'll look on Clark's about checking the AFM and TPS. I want to switch to an MAF eventually, so if the AFM is bad I'll probably push that to the top of the list. A chip would be a good investment anyway, but like with the exhaust I was hoping to wait until I had several other mods done to avoid doing it more than once.

Thanks again for giving me some paths to try. It's when I'm out of things to try that I begin to get discouraged.

Chuck Henry

Well, the AFM and TPS checked out, but there were little things. Even though the AFM tested good, I did have grooves so I repositioned the swing arm just to be safe. The TPS also checked out, but it was just off from getting the "click" for idle so I adjusted that as well. It's icy around the house right now so I didn't drive it to see if there was a difference. I don't expect those changes to make a difference, but we'll try the O2 sensor next if not. I also want to jump the altitude sensor to see if that makes a difference. Should have done that while I had the DME out, but didn't want to change to many things at once. Makes it harder to know what the problem was for next time.