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All kinds of good ideas here but this one caught my eye.
...but I have adjusted the throttle screw for idle (installed a new screw as old one was leaking air)...
I thought they were supposed to leak (a tiny bit).
Test by... Jumper the test plug to defeat closed loop idle adjust. Then tweak the screw (which allows a tiny bit of air to bleed into the throttle body) for correct RPM . Pull the jumper. Drive on.
All kinds of good ideas here but this one caught my eye.
I thought they were supposed to leak (a tiny bit).
Test by... Jumper the test plug to defeat closed loop idle adjust. Then tweak the screw (which allows a tiny bit of air to bleed into the throttle body) for correct RPM . Pull the jumper. Drive on.
When you tweak it, does it alter the RPM?...Bruce
There were bubbles galore coming out of the old idle screw during low-pressure testing; now, nothing. I would imagine a new screw (comes with seal) should be proper?
Yes, as I was tweaking it —ICV jumpered— the rpm was changing. I did my best to set it so that there is no change when the ICV is back in. At the emissions test, it shows 880rpm. They put a wire into the cigarette lighter to read rpm (?)
The ICV operates in open and closed loop. Think of cold start idle speed. Do not think you can use this as a closed loop discriminator. Not sure there are any places to test, other than O2. Will think about the problem.
I replaced the CO test pipe with the official cap nut but I can put it back. Problem is, where am I gonna find a place that has the testing equipmemt (and still uses it)?
That O2 sensor is brand new Bosch; but, I did notice a slightly worse fail after I installed it.
Two questions:
1. Can fuel pressure affect idle afr but not higher rpm?
2. Can a malfunctioning evap system cause the rich idle?
The only other thing I can think of currently is that the rotor, cap, and wires are on the older side
If you changed to 3.0 bar pressure regulator, yes will run rich, need to burn new set of chips. I changed mine for the 3 Bar Reg. You said stock
malfunctioning evap is a broad subject, typically will look like an air leak and make the engine more lean.
There is a setting on the DME, covered in Clarks Garage, to lean out fuel with a golf Tee to turn the rotary switch. From memory can get 4-6% lean. Well described on Clarks (RIP) page
Need to do some math and determine how far out. Then look at plugs to see if localized to certain cylinders, to isolate injector issues. Based on your numbers the plugs will all be sooty, or specific cylinders. Check after 5 min idle. May try temp gun on exhaust flange, rich will be cooler.
Last edited by Alan 91 C2; 04-25-2018 at 07:05 PM.
The 944 is electronic fuel injection. So the mechanical thinks you have the mechanical fuel injection. He can not adjust CO on electrical injection. On the mechanical system there is a screw to adjust CO. (I have a 77 924 with mechanical injection.)
The FQS is your easy option. But look at the plugs to make sure you have a uniform issue, not a specific injector issue.
The 944 is electronic fuel injection. So the mechanical thinks you have the mechanical fuel injection. He can not adjust CO on electrical injection. On the mechanical system there is a screw to adjust CO. (I have a 77 924 with mechanical injection.)
The FQS is your easy option. But look at the plugs to make sure you have a uniform issue, not a specific injector issue.
Hmm.. I've read a procedure in the WSM on adjusting the CO at the AFM. There's a screw to turn (see pic).
You are supposed to use a gas analyser on the CO tube. Of course, I reckon this should only be done if all other systems are operating properly.
That's why I'm first going to test fuel pressure and check the plugs as you suggest. After that, I think I've ruled everything out. Big assumption lol
Hey I'm thinking instead of paying for tests to keep troubleshooting, I could buy a CO meter. There are some reasonable ones out there... https://sensorcon-sensing-products-b...motivecometers and instead of paying the mechanic for an hour, I could have one of these and use.. forever
I wonder if they work? It would be nice knowing what it's at *before* going to the test center yet again
Ok, so yesterday, on the way home from work, a funny thing happened: this little coolant hose connection on the rad broke--inside the thread! It's #27 in the diagram (yes, I know this is for NA, but this part is the same) and in front of the red circle
When I got home (incredibly with just enough coolant to keep it from overheating), wanting to keep the car on the road, I installed this old Volvo 850 rad drain plug I had lying around. It's the same fit, and, the hose fits on the end which is oddly shaped like a hose barb. Magic! Filled up the system, bled, and drove to work today. Felt like a real mechanic!
Then I realized I didn't drill out the replacement. So, the circled hose above is actually blocked off.
BUT... get this: the temperature is now behaving amazingly excellent. Instead of running at a 9 o'clock to 9:30 positiion as it's been for last year, it's now running a nice 8:30-9 o'clock on the dial. Even after some serious stop-and-go traffic in pretty warm weather, it never gets past 9 o'clock. I don't remember it every being this solid!
The engine even feels noticeably cooler to the touch.
Obviously, I'm going to restore this little hose's function soon enough.. but.. perhaps there's greater success in filling / bleeding with that hose crimped off?
Even more importantly (and relevant to this thread), could this new-found cooling behaviour solve my poor idle CO score? Conversely, wondering if a slightly warmer running engine (EDIT: maybe this had something to do with my slight rad leak in this area that I now think was a combo of this plug cracking and end tank seals that I fixed) throw off the idle afr enough to mess my idle CO....
I kinda want to keep the Volvo part in there hehehe
Um.. as I picture that Volvo part I put in as a temp fix on my broken rad upper nipple, I'm thinking it might be "drilled through" or open. I can't find a photo of it looking into the end I got the hose on, but the other end suggests it's a petcock that drains when slightly unscrewed? Indeed, some parts places call it a petcock.
If that's the case, I'm leaving it in and enjoying my new-found factory-cool running system! Can anyone confirm?
04-24-2018, 01:57 PM
