Freshly rebuilt pump, slightly high idle and some smoke

Technical questions and answers concerning all models of VW diesel vehicles.

Moderator: Fatmobile

Una
Cetane Booster
Posts: 76
Joined: Sun Jun 12, 2011 12:25 pm
Location: Olalla, WA
Contact:

Freshly rebuilt pump, slightly high idle and some smoke

Post by Una »

I finished installing my rebuilt pump yesterday. I did my best to set the timing on it. Seemed like every time I'd rotate the engine a couple turns and re-check my setting, it'd be a slightly different reading than the time before... I read a half dozen methods for setting the timing online, they're all pretty much the same. I'm not sure why I had so much trouble getting a consistant reading. I believe I set the pump to .033"-.038", depending on which reading you go by. I aimed for .038", but saw .033" on a double check. Both are in tolerance, and I had rechecked and readjusted about 5 times at that point, so I called it good and moved on.
I was happy to have an AC vacuum pump when it came time to prime the pump, it took quite a while before it finally pulled fuel all the way through the thing.
It fired up relatively easy. Seems a little noisier than before, but I'm not totally sure on that one, it's always been a stunningly noisy engine (in the 3 weeks I've owned the car). Throttle response is nothing short of amazing, crisp and fast revving in neutral.
But the idle seems kind of high, maybe 1200-1400rpm, since I have to guess.. I tried loosening and turning down the throttle stop screw, didn't help much, and I quickly found a spot where the engine just wanted to die, so I got as close to that without reaching that as I could. Still seems higher than it should be.
And finally, this pump seems to have more throttle to it.. My old one, I'd get to about half throttle and more throttle did nothing beyond that, except maybe at high RPM's which I don't tend to go to.. But this new pump, there's more power up there, but it comes with a noticeable amount of smoke out the back end. When it's not smoking but I am driving it hard, I get a "rabbit sized" cloud when I lift off the throttle to shift.
I've heard of the "smoke screw", should I back that out some? Should I limp the car over to a "professional" who can set the timing without so much uncertainty?
The pump came from Jack, so I have no doubt it's good and was rebuilt perfectly, I'm sure it's all me, and maybe some fine tuning for my particular motor. Maybe my readings were WAY off, and the thing is way too advanced? I never noticed the advance lever having an effect on idle speed before, though (still doesn't) so I don't see how advanced timing would be raising my idle speed.
'81 Diesel Rabbit
'88 Dodge Omni
82vdub
Turbo Charger
Posts: 4922
Joined: Wed Jun 20, 2007 1:44 pm
Location: Green Bay, WI
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by 82vdub »

As for the timing dial gauge readings, I wouldn't worry about that much. You can fine adjust how you want it to run without a dial gauge if you want. As for the engine speed, are you sure that the throttle cable isn't holding the throttle partly open and that the springs on the throttle lever are installed properly? I've actually had the throttle setup (on the top of the IP) stick slightly on a rebuilt pump. If I let off the gas easily, it would hang up on me, but if I quickly let off the throttle, it would drop to idle. It got really bad on a trip to Iowa, so I pulled over, pulled out a quart of spare engine oil, and dumped some on top of the bolt that holds the springs on top of the IP throttle assembly. Worked fine ever since.

I've never messed with the smoke screw. There's links all over that talk about adjusting that to eliminate the smoke coming out the back. Adjusting that will address the smoke issue.
Everybody else lists their cars here - but not me.

I have too many to count
Una
Cetane Booster
Posts: 76
Joined: Sun Jun 12, 2011 12:25 pm
Location: Olalla, WA
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by Una »

Cool, that's kind of what I was thinking. I started it up this morning, granted, it's not cold out, probably 60f, but hadn't been started in 14 hours or so, and it fired up so fast I couldn't let go of the key fast enough. So the timing can't be THAT far off. It did seem like it wanted me to press the cold start lever in immediately, so if I had to guess, I'd say it's a bit more advanced than it should be.
I do have some freeplay in the throttle cable still, and pressing the arm on the IP towards the closed position didn't lower the idle. Those were some of the same thoughts I had. Thanks for the tips, I'll play with it some more. :)
'81 Diesel Rabbit
'88 Dodge Omni
82vdub
Turbo Charger
Posts: 4922
Joined: Wed Jun 20, 2007 1:44 pm
Location: Green Bay, WI
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by 82vdub »

The high idle speed probably isn't much of an issue, if it doesn't bother you too much and you don't worry about the little extra fuel that would be consumed from the faster engine speed. Maybe just run it?

A properly adjusted timing would have the engine sounding like marbles dancing on a plate when the cold start lever is pulled. You don't want to advance the static timing too far. Just enough for good starts and a slightly more noisy engine when you pull the cold start cable.
Everybody else lists their cars here - but not me.

I have too many to count
TylerDurden
Turbo Charger
Posts: 1285
Joined: Tue Dec 22, 2009 1:01 pm
Location: Michigami, USA

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by TylerDurden »

IIRC, the smoke-screw also affects idle speed. Reducing the smoke may also reduce the idle speed.

Some smoke is not bad - overfuellling provides more power at the expense of efficiency.
Have a nice day.


'91 Jetta ECOdiesel TD - clean & complete (less motor/tranny) for sale

'82 Westy Vanagon 1.9 N/A - 23.5mpg
'86 Jetta TD - 45-50mpg
'81 Dasher Wagon 1.6 N/A - 52mpg
'84 Wasserboxer - DOA, parts donor
'94 Passat wagon VR6
'03 Jetta TDI wagon 230K, 52.3mpg
'89 Jetta N/A - 51mpg
'82 Caddy 1.6 N/A - Sold
Una
Cetane Booster
Posts: 76
Joined: Sun Jun 12, 2011 12:25 pm
Location: Olalla, WA
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by Una »

Will the extra fuel cause the engine to run hotter at all? I believe I read that on a diesel, more fuel makes for higher EGT's..?
'81 Diesel Rabbit
'88 Dodge Omni
82vdub
Turbo Charger
Posts: 4922
Joined: Wed Jun 20, 2007 1:44 pm
Location: Green Bay, WI
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by 82vdub »

It could cause it to run a little hotter. Whether you'd notice it or not, I wouldn't think it would cause it to run that much hotter, unless you're dumping fuel in.
Everybody else lists their cars here - but not me.

I have too many to count
Una
Cetane Booster
Posts: 76
Joined: Sun Jun 12, 2011 12:25 pm
Location: Olalla, WA
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by Una »

I ran my first tank of fuel through the new pump this week. I got 49mpg out of it. Then I finally went and played with that smoke screw, I did it while it was running and idling at it's usual high (1500ish RPM) idle. The second I cracked that lock nut loose the idle started to drop, I think I turned it 3/4 of a turn and the idle was good and low, probably 800rpm. Seemed to smoke a bit less after that, but I'll see how it goes. I may have to turn the throttle stop screw back up to where it had originally been, and bring the smoke screw down a bit more. Just thought I'd post my results, since nobody else seems to have encountered this problem before...
'81 Diesel Rabbit
'88 Dodge Omni
TylerDurden
Turbo Charger
Posts: 1285
Joined: Tue Dec 22, 2009 1:01 pm
Location: Michigami, USA

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by TylerDurden »

49mpg and a little smoke sounds pretty good to me.
Have a nice day.


'91 Jetta ECOdiesel TD - clean & complete (less motor/tranny) for sale

'82 Westy Vanagon 1.9 N/A - 23.5mpg
'86 Jetta TD - 45-50mpg
'81 Dasher Wagon 1.6 N/A - 52mpg
'84 Wasserboxer - DOA, parts donor
'94 Passat wagon VR6
'03 Jetta TDI wagon 230K, 52.3mpg
'89 Jetta N/A - 51mpg
'82 Caddy 1.6 N/A - Sold
Una
Cetane Booster
Posts: 76
Joined: Sun Jun 12, 2011 12:25 pm
Location: Olalla, WA
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by Una »

It wasn't what I'd call a little smoke. I could fog cars behind me at will. And the 1500rpm idle was driving me nuts.
'81 Diesel Rabbit
'88 Dodge Omni
DanHoug
Turbo Charger
Posts: 311
Joined: Fri Apr 23, 2010 10:42 pm
Location: Bemidji, MN
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by DanHoug »

having just got done tuning my smoke screw, it absolutely affects idle speed. i had to turn it out and increase idle speed with each adjustment.

-dan
'91 Jetta NA on WVO for 120k miles
'91 Jetta ECO
fritz
Glow Plug
Posts: 2
Joined: Thu Jul 28, 2011 12:38 pm

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by fritz »

I read the below quote, was wondering if this applies in general?
I have a '96 eurovan transporter and it smokes and stutters a little on the hiway, and if i pull out the cold start lever it runs smooth and quiet.
does this mean my timing needs a little adjustment? Is that easy to do?

Thanks.
82vdub wrote:The high idle speed probably isn't much of an issue, if it doesn't bother you too much and you don't worry about the little extra fuel that would be consumed from the faster engine speed. Maybe just run it?

A properly adjusted timing would have the engine sounding like marbles dancing on a plate when the cold start lever is pulled. You don't want to advance the static timing too far. Just enough for good starts and a slightly more noisy engine when you pull the cold start cable.
DanHoug
Turbo Charger
Posts: 311
Joined: Fri Apr 23, 2010 10:42 pm
Location: Bemidji, MN
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by DanHoug »

yes, it sounds like the timing is too retarded. does it run better warm? cold, the engines like more advance but it could smooth out once warm. but there can still be too little advance to run decent when warm.

there is much information within the archives on adjusting timing, either by gauge or by feel. sit down with a large pot of coffee and start reading past threads on IP timing. since you now own a diesel, you now need to purchase the Bentley manual for your vehicle. it is all revealed in the Bentley.

-dan
'91 Jetta NA on WVO for 120k miles
'91 Jetta ECO
82vdub
Turbo Charger
Posts: 4922
Joined: Wed Jun 20, 2007 1:44 pm
Location: Green Bay, WI
Contact:

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by 82vdub »

Yes, advance the timing by rotating the IP towards the head.
Everybody else lists their cars here - but not me.

I have too many to count
fritz
Glow Plug
Posts: 2
Joined: Thu Jul 28, 2011 12:38 pm

Re: Freshly rebuilt pump, slightly high idle and some smoke

Post by fritz »

Will purchase Bentley.

No, it doesn't run better warm, bout the same.

I'll look into the IP timing...
thx
Post Reply