2.3L GoWesty Hesitation and Intake Pop When Warm

[DanHoug]

each time the brake pedal is pressed, the vacuum booster releases air into the rather large diameter vacuum line attached to the intake manifold. repeatedly pressing the pedal would be akin to a substantial unmetered air leak and it makes sense you see the mix go lean.

the Digifant idle/WOT switch operation in combination with the ECU shuts off ALL injector opening until the RPM is below about 2000. so there should be zero bucking on in-gear deceleration until that point below 2000 where the ECU switches injector pulses back on. if you are experiencing bucking on decel ABOVE 2000 rpm, you have a switch issue as the fuel is SUPPOSED to be cut off completely.
_________________
-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Wildthings]

On a Digijet the decel cut "OFF" RPM is the same as the "ON" on RPM, which can easily lead to bucking, whereas with the later Digifant the decel cut off function was improved upon to make it so there was a significant difference between the cut off rpm and the cut on rpm which eliminated the bucking issue.

[Mr.LowPower]

Perfect that explains the brake pedal thing, as for the bucking on deacceleration, lets not worry too much about that for now.

Today I threw in the Bosch Fuel pump, and a new filter. Bosch is definitely quieter, however its hard to tell if there is any major change as last night I went a little crazy trying to re-adjust my timing and tweak little things on my AFM. Today I tried to put my timing back to where it was, however I was having a hell of a time getting the engine to run like it did before which was still far from perfect. When I bypass my idle control unit, disconnect/plug the 2 vacuum lines from the distributor, I CANNOT get my van to idle at @ 850rpm. The engine either idles consistently at 1000 rpm with the idle screw on the throttle body all the way in. Or it pulses from 1000 to 1300, and back down to 1000, over and over. Only way to stop the pulsating idle is to screw in that throttle body adjustment screw, however I feel it should NOT be all the way in. Regardless how it idles if I set timing anything more retarded than 35Deg BTDC @ 3000rpm the idle will be super slow and lethargic almost as if its about to stall until I plug my idle stabilizer back in. In which case it will idle good for the first few minutes, then the engine will REALLY lean out and bog down when I apply throttle. Currently I have it set past my 35deg mark which I don't think is correct as GoWesty explicitly states 35 degrees should be the MAX.

[Wildthings]

[Mr.LowPower]

Inserted a screwdriver into cylinder 1. Verified TDC is in line with the U mark. When idling I try to set my timing to 5deg ATDC which would be the V mark. When do do this the car will idle fine, but the bog whenever I apply the throttle is very pronounced and ultimately un-drivable. It runs 'best' when I set it to 35deg BTDC at 3000rpm but it's still not perfect.

After playing with the AFM it seems like I either have a timing issue, or a vacuum leak I cannot pinpoint.

[Wildthings]

[do.dah]

I'm curious, has your van been sitting mostly for the last year, since you've installed the new engine? Sitting since it's basically undrivable due to this issue?

Did you put your old throttle body onto the new engine?

Did you go thru the procedure to adjust the air/fuel mix?

I just spent a few minutes looking at the GoWesty engines, and they seem to just use generic descriptors for their engines, with a few notations/exceptions for certain engines.

Nontheless, it sorta seems that the 2.3 gets a reground crankshaft(stroked). Which will change your timing from factory 2.1.
If you just stuck your old throttlebody on without adjusting air/fuel,,, with the larger engine,, you'd probably have some other problems.

I kinda think here, that you either go to a good mechanic that has an exhaust sniffer to adjust your air/fuel mix with a timing setting somewhat higher than the stock 2.1, or, perhaps one of those wideband O2 sensors(Sorry, can't remember if you already have one of those), to dial in air/fuel.

Additionally, GoWesty recommends higher octane. Personally, I think 89 is too low. My engine builder stressed to me to use the highest octane I could get.

[Mr.LowPower]

[Ahwahnee]

[Wildthings]

[Mr.LowPower]

After fighting with the timing for quite some time my problem still presists. Right now it truly seems to be happiest around 35° BTDC @ 3000rpm. But no matter where I am it just doesn't run as it should, always seems to bog on me.

I'm going to go pickup a vacuum gauge this afternoon. What values should I be looking for? And what lines should I check.

Someone suggested i take some propane and check for vacuum leaks by listening for any changes in idle. No dice... I even pulled off one of the vacuum lines for the distributor and let the propane lean in. No change which I thought was strange.

[Wildthings]

Did you do the test I suggest where you remove and plug the retard hose while the engine is idling and see how much the rpm changes?

What does the exhaust sound like? It is a low throaty sound? or more of a whistle?

[Mr.LowPower]

WildThings, with everything connected I would describe idle as low and throaty, when I disconnect the hose towards the rear of the van, the idle stays roughly the same, sounds like it increases audibly but according to my tach not really any faster. Sound has a slightly higher tone however I would not call it a whistle, still low and throaty.