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Discussion Starter · #1 ·
My E30 has been running like crap, and after replacing most of the usual suspects*, I'm down to a few things to try, one of which is a smoke test to find vacuum leaks in the intake (I tried starter fluid - no luck). I recently stumbled across this:

http://forum.e46fanatics.com/showthread.php?t=445181
jbeurotech said:
Build this smoke machine for under $30 and be able to find vaccum leaks the correct way!! Carb clean will not show most vaccum leaks, this will help you find those very small vaccum leaks!! This inert smoke will fill the intake and leak out the smallest leaks, indicating where you have an issue. This is the only way to properly find a vaccum leak!! Our profesional machines work better. However most of you DIY's do not have the money to drop on the tools that we use. But this will get you close!!

Anyone do one of these before? Got any tips? This looks promising. I hear (later in that thread) the ACDELCO 60Gs are the way to go for the glow plug.



* those would be: air flow meter, intake boot, fuel pressure regulator, coolant temp sensor, idle control valve (tested), throttle position sensor (tested), plugs, wires, cap, rotor, coil, ecu
 

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Ha, that is a pretty cool idea. Probably very useful for the older VW's where vacuum leaks are especially troublesome. If it's under $30 to build, I can see it being a good value for your average automotive tinkerer.

On side note, what's the issue you're having with the E30? What motor do you have?
 

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Discussion Starter · #5 ·
Late ('91) 'i' motor (M20B25, Motronic 1.1).

Full description from my thread over on e30tech:

It starts and idles okay, then at a certain point in warm up it starts to idle much worse and will usually stall if I let it. If I drive it, it basically can't move on anything more than level ground, and even there it sputters and knocks. If you give it any throttle while you're in gear it just gets worse.

Once it's almost all the way up to running temp, it's like a switch flips and it gets a lot better (I assume this is the ECU switching from cold start to regular programming). Most of the time it pulls at somewhere between 60% and 80% without too much choppiness, every once in a while it'll actually give me 100%.

It occasionally throws a CEL and logs 1222 (the generic Lambda Control #1 code, aka "something's wrong and you should fix it"). As soon as the CEL comes on, it starts running worse, and then when the CEL goes out, it runs better. Usually (but not always) the CEL comes on under light, constant throttle.

The only thing that seems to make a difference is that when I disconnect the O2, it runs warm exactly like it does when warming up. This doesn't make any sense, though, since plenty of people drive with no O2 with no drivability issues. My guess here is that whatever the real problem is is bad enough for the ECU, when I disconnect the O2 it has one less data point and really starts to struggle. It also logs a 1221 (O2 code) when I do this, and it doesn't any other time, which leads me further to believe that's a red herring.

The last time I drove it it was driving just as bad once warm as it does while warming up, although intermittently.
 

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I think that you are running 1.3, not 1.1. You have a 173 DME, correct?

Did you try the usual sensors in this case (coolant temp, IACV, AFM)?
 

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Discussion Starter · #7 ·
I think that you are running 1.3, not 1.1. You have a 173 DME, correct?

Did you try the usual sensors in this case (coolant temp, IACV, AFM)?
Pretty sure it's the 173, but I'd have to pull again to check. I know the VIN matched so I guess it has to be.

CTS replaced, AFM swapped with known good, IACV bench tested good.
 

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I'd have the car run, and start unplugging sensors and see if the idle changes a bit. If you pull a conenctor and there is no change, that sensor is your problem. I've had the same thing happen to me.

Have an air leak at all?

173 on a 91 'i' is definitely M1.3
 

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thought this was going to be a thread about seafoam :rolleyes:
 

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Discussion Starter · #10 ·
I'd have the car run, and start unplugging sensors and see if the idle changes a bit. If you pull a conenctor and there is no change, that sensor is your problem. I've had the same thing happen to me.
Yeah, I didn't think of that until a friend suggested it a couple days ago. So I'll give it a shot.

Have an air leak at all?
Well that's kinda what I'm trying to find out by building a smoke machine...
 

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Well that's kinda what I'm trying to find out by building a smoke machine...
Riiight.

If the car runs smooth at any time, you don't have an air leak. That's somethign taht would be constant despite the engine temp. If the car is running, get real close and listen for the telltale vacuun air noise. In my case, the hose that was below the TPS had blown off.

I'd put money towards a bummed sensor. Worry about the smoke machine once you have rulled out all the sensors sicne they are easy to check.
 

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Late ('91) 'i' motor (M20B25, Motronic 1.1).

Full description from my thread over on e30tech:

It starts and idles okay, then at a certain point in warm up it starts to idle much worse and will usually stall if I let it. If I drive it, it basically can't move on anything more than level ground, and even there it sputters and knocks. If you give it any throttle while you're in gear it just gets worse.
Misfire. It says you changed the coil but was it installed properly?
 

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Discussion Starter · #14 ·
It's pretty simple, the connectors are two different sizes so they can only go on the posts one way, and then make sure the distributor wire is fully seated... is there something else?
 
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