New engine build

vwlover77 · Post by **vwlover77** » Thu May 08, 2008 11:44 am

IFBwax wrote:I would agree with you Don. I have not played with the AFM but I'd bet it would help, but then you would be probably way rich when it's warm. What are you thinking? Boosting the cold start injector?

Well, if it were me, and richer made it run better, I'd be tempted (there I go again!) to rig up a switch up at the dash that would connect a resistor in series with the CHT sensor. At cold start and during warmup, I'd flip the switch, which would fool the ECU into thinking the engine is colder than it really is, causing it to enrich the mixture. After a few minutes to warm up, flip the switch "off" and the CHT feeds straight through to the ECU again.

I'd use a variable resistor to start with to get the ballpark resistance value needed, then go buy the fixed value resistor of the same value.

steve74baywin · Post by **steve74baywin** » Thu May 08, 2008 11:47 am

vwlover77 wrote: Well, if it were me, and richer made it run better, I'd be tempted (there I go again!) to rig up a switch up at the dash that would connect a resistor in series with the CHT sensor. At cold start and during warmup, I'd flip the switch, which would fool the ECU into thinking the engine is colder than it really is, causing it to enrich the mixture. After a few minutes to warm up, flip the switch "off" and the CHT feeds straight through to the ECU again.

I'd use a variable resistor to start with to get the ballpark resistance value needed, then go buy the fixed value resistor of the same value.

I have thought the same thing Don a while back..

cheesehead · Post by **cheesehead** » Thu May 08, 2008 11:54 am

I'll chime in here and say that I too have a rough idle at first but not for very long at all but I have CS with dual Weber's. I thought it was indicative of the carbs hmmm.
Meg

vwlover77 · Post by **vwlover77** » Thu May 08, 2008 11:57 am

When I was trying to get my low-CR performance-cam engine to run right (impossible, BTW), I actually had a variable resistor wired up into the cab so I could dial it while driving. It's amazing how it would go from nice "crisp" response to running so rich that it had no power and was putting black smoke out the exhaust - just by turning the little knob!

Westy78 · Post by **Westy78** » Thu May 08, 2008 4:37 pm

Interesting that you guys have touched on enriching the mixture to even out the cold idle. I was going to post something today about my findings about the cold idle. I currently have the LM1 wide band AFR meter hooked up and I noticed yesterday that at first start up the mixture is in fact very lean (into the 20.0+ to 1.0 zone). At first I thought that I might have a vacuum leak but after spraying every leak point with starter fluid last night I couldn't find a one. It seems that once my heads hit about 300° it smooths right out and idles like normal. I wonder if adjusting the AAV to be more restrictive would help in the first few minutes of warm up. I had always thought that not enough air was being injected with a rough cold idle but perhaps it's just the opposite with the Camper Specials. I'll have to go play with the wiper next time I start it up and see what the engine is wanting.

vwlover77 · Post by **vwlover77** » Thu May 08, 2008 5:28 pm

Westy78 wrote:I wonder if adjusting the AAV to be more restrictive would help in the first few minutes of warm up

The Auxiliary Air Regulator does not send un-metered air into the engine. The air that passes through it does flow through the AFM first. Its effect is exactly like opening the throttle slightly. In fact, you may want to open it up more to give you a faster idle at cold start. It's easy - just loosen the little nut and slide it whichever direction gives the largest opening.

Westy78 · Post by **Westy78** » Thu May 08, 2008 8:46 pm

You're right Don. I wasn't thinking about metered and unmetered.

So I went out and fired the engine up to see where the mixture was. I'm not sure what's going on but the meter says it's running very lean, up into the high 20's to low 30's but it smells as though it's running rich. Moving the potentiometer in either direction didn't make it any better, in fact worse in both directions. I have no exhaust leaks (to give a false lean reading) and again couldn't find any vacuum leaks. It sounds as though it's a miss in the ignition until it's warmed up but a miss would make a richer mixture due to unburned fuel in the exhaust right? Odd. Maybe I'll pull the AAR and make sure it's operating correctly and while I'm at it I'll adjust it to open further when cold.

solexes@hotmail.com · Post by **solexes@hotmail.com** » Thu May 08, 2008 9:52 pm

So I went out and fired the engine up to see where the mixture was. I'm not sure what's going on but the meter says it's running very lean, up into the high 20's to low 30's but it smells as though it's running rich. Moving the potentiometer in either direction didn't make it any better, in fact worse in both directions. I have no exhaust leaks (to give a false lean reading) and again couldn't find any vacuum leaks. It sounds as though it's a miss in the ignition until it's warmed up but a miss would make a richer mixture due to unburned fuel in the exhaust right? Odd. Maybe I'll pull the AAR and make sure it's operating correctly and while I'm at it I'll adjust it to open further when cold.

Ironicly I suffer from the exact same problem - I was chaulking it up to bad seals on the dipstick and oil filler - but I don't know.

Obie and I were looking at some gas analyzer readings - and I looked to be REALLY lean - but it smelled REALLY rich.

Installing the right crank case breater hose fixed this problem (I had a leaky original on there before). But -----.....

I too have the rough idle - not owning a stock VW for long enough - I thought this was normal - after a minute it is a smoother idle - and at about 250 on the temp readings - it smooths out.

Wondering if the FI is being taxed by the CS a tad....

I have over 5k on mine so far.....what a great engine!

Westy78 · Post by **Westy78** » Thu May 08, 2008 10:25 pm

This is interesting. What is that now, four CS engines with the cold idle problem? Maybe this is just going to be a characteristic. Not a huge deal, it runs great once warmed up. I am having some "hunting" in the warm idle though. Not extreme but it will idle at about 1000-1100rpm then drop to around 900 or so for a few seconds and then recover to the higher idle. I think I'm going to check on the fuel pressure the next chance I get. Don't know if that has anything to do with any of it but it just popped into my head as something to rule out.

Westy78 · Post by **Westy78** » Thu May 08, 2008 11:48 pm

Fresh footage of the beast. This is after idling for about five minutes. Hear anything out of order?

Click on the "watch in high quality" link right below the video for much better picture.

http://www.youtube.com/watch?v=UMycdc8tqRA

Mr Blotto · Post by **Mr Blotto** » Fri May 09, 2008 4:38 am

Westy78 wrote:Fresh footage of the beast. This is after idling for about five minutes. Hear anything out of order?

http://www.youtube.com/watch?v=UMycdc8tqRA

Cool

Nice of your dog to make a cameo

germansupplyscott · Post by **germansupplyscott** » Fri May 09, 2008 2:20 pm

get an extra throttle valve and drill a 3/32" hole in the throttle plate. re-adjust idle and you might have to play with the AAv to get perfect warmup idle rpms.

Westy78 · Post by **Westy78** » Fri May 09, 2008 3:15 pm

germansupplyscott wrote:get an extra throttle valve and drill a 3/32" hole in the throttle plate. re-adjust idle and you might have to play with the AAv to get perfect warmup idle rpms.

I've heard about this mod. Anywhere in particular that you drill the hole? I'm assuming somewhere on the top side of the butterfly. I have an extra throttle body that I can play with.

Post by **Amskeptic** » Fri May 09, 2008 5:09 pm

Westy78 wrote:This is interesting. What is that now, four CS engines with the cold idle problem? Maybe this is just going to be a characteristic. Not a huge deal, it runs great once warmed up. I am having some "hunting" in the warm idle though. Not extreme but it will idle at about 1000-1100rpm then drop to around 900 or so for a few seconds and then recover to the higher idle. I think I'm going to check on the fuel pressure the next chance I get. Don't know if that has anything to do with any of it but it just popped into my head as something to rule out.

BEFORE YOU ALL START DRILLING OUT YER DAMN THROTTLE PLATES, how about if we let your poor engines break in? You have lots of new engine friction for at least the first 1,000 to 2,000 miles.
Sheesh,
Colin

Westy78 · Post by **Westy78** » Fri May 09, 2008 5:13 pm

True Colin, I won't be doing anything to mine for quite awhile. However I think Wayne has over 3k miles on his and Ryan is at over 5k. I'm pretty sure Casey has even more. Shouldn't their engines be sufficiently over the break in period?

Itinerant Air-Cooled

Itinerant Air-Cooled

New engine build