In six months, I have never gotten my car to run right. I changed and cleaned and serviced many items. Recently, I checked vacuum at idle and it was below 7. I built a test setup to find leaks on the manifold. I found several and fixed them. The manifold holds vacuum. Now vacuum is above 10 at idle, but not to 15. If anyone has a 2.0L that is running properly I would love to know what your vacuum reading at idle is. Please provide the value after the AFR has closed as that valve changes the plenum vacuum.

The car runs no better now, and I need some baseline to satisfy myself that I have fixed all the leaks.

Thanks.

Tim

Hahahahahaha


Seriously though... I guess mine is running pretty good. I can give it a try tomorrow.

I'd be looking at your valves being too tight, timing retarded possibly. If these are good then I'd do a leak down check. Have you checked the compression readings on the cylinders?

Last I checked mine I think it was ~17inHg at idle.
What is your RPMs at idle when your engine is warm and the AAR (not AFR) is fully closed?

Just checked mine. Cold start, cold 30f this morning. 17inches. Funny thing is the aar didn't matter to the vacuum much. I thought that was a little surprising. Aar on it would drop down to maybe 15 or 16 but of course idle dropped considerably when I closed it (I have a valve on my aar hose).

Just some specs..
My idle hot is 850
Cold aar open rpm starts around 1k and climbs to 1500ish as the engine warms and the aar is open.
Just dynoed the car on Saturday so pretty sure it is running as good as it can be considering the age.

Per my Microsquirt logs...once warmed up at 0% throttle, 23.0-23.5 kPa.

2056, mild cam, stock 2L induction bits.

(I love data...)

i think mine was 15-17 when i checked it after installation and when i was working on the tune etc. 2.1, d-jet stock bits, mild cam etc. might recheck this again to make sure. i think my engine builder said they like to see 17-20 on F.I.

I adjusted valves. Pretty sure they are spot on. I am able to improve idle and vacuum by cupping my hand over the intake, reducing how much air gets through. Idle smooths out and AFR gets richer.

I will check compression. Will be some time as the holidays have me driving about 100 hours over the next few weeks.

Thanks.

Idle is 950 and vacuum is about 12 with engine warm.

I am building a pressure tester to connect to the AAR tube when it's cold. I will pump compressed air into the manifold and use soapy water to look for leaks.

Again, given my schedule, it will be a while. But I should be able to find almost any external leak with this method. If there are no leaks and I still have low vacuum and compression test is bad, I will double check the valve clearance.

Thanks. I don't think I can get it that high, but I am clearly way down the scale.

Thanks. I will shoot for 17. Seems like an attainable number.

From the Bosch guide:

Jeff,

I saw that last night That's where I got the idea. We will see if anything shows up.

Make a cheap DIY smoke machine. You'll find any leaks quickly.

Thanks

Cold compression test results

1 2 3 4
100 90 70 105

That 70 is worrisome. PLugs out? I would try it warm...

You won't get high vacuum readings with the compression low. I'd do a leak down check next to see where your internal problems are at.

Plugs all out. I don't think further testing is needed. These numbers are so marginal
I am pretty sure the engine is toast. I am prepping to drop the engine. Tranny needs attention anyway. When I get it put together, I can test it on a bench before putting it back in.

Thanks for the response.

Please define leak down. Run compression check and see how long it holds?

Thanks.

Please define leak down.

Thanks.

I studied up on leak down. I don't have gauges, but I can blow air into the cylinder and listen to where it's coming out. Very useful.

Thanks.

With any luck you just have poor sealing on the valves and not piston issues.