CIS guru's needed!! 83' SC cold start issue

[Bob Kontak]

Originally Posted by pmead

I did not need the old one calibrated because I had sent in a "089" core to flowtech in partial exchange for the correct 090.

Interesting.

My 81 US had an 089 on it and I replaced with a new 090 in about 2002.

Maybe it was the "hot" setup in the 80's to replace the 090 with the 089 given a touch richer.

[pmead]

When I bought the car it had the 089 WUR. I am not sure why. The PO did not know it was the wrong part. The car never ran correctly with it. I found a used 090 to make it correct for the car. Tony tested the used one and it was out of spec. I used the 089 for a core and got a "new" 090 from Flowtech and then sold the used 090 as a core in Hershey this spring. When I get home from work I plan running another pressure test with accurate temperatures to make sure this new WUR is in spec.

[pmead]

OK, performed another fuel pressure test tonight.

System 4.7bar
cold control @16c 1.5
warm control 3.5 (1.8@30sec, 2.2@1min, 2.6@1min30sec, 3.0@2min,
3.3@2min30sec, 3.5@3min, 3.5@4min)
residual 1.8 after 10min

According to Bentley my Cold control is a little low again. I am not sure if it is off enough to effect my cold start though. This indicates a slightly rich condition. If my mixture is already a little rich could this compound the problem with the low CC pressure and cause the idle surge/drop on the 1st start???

[boyt911sc]

Originally Posted by Bob Kontak

Interesting.

My 81 US had an 089 on it and I replaced with a new 090 in about 2002.

Maybe it was the "hot" setup in the 80's to replace the 090 with the 089 given a touch richer.

Bob K.,

These two (2) warm up regulators are totally different in both its operation and function. People interchanged them in the past due to lack of knowledge or technical information. Time has changed.

WUR-089:
Vacuum assisted
Single heating element
Used in non-lambda engines
Needs a thermotime valve

WUR-090:
Non-vacuum assisted
Multi-heating elements
Used in lambda engines
No need for a thermotime valve

If you place them side by side, you will see the physical differences between these two.
With the advent of Internet, we get better information and communication each day.

Tony

[Reiver]

Originally Posted by Bob Kontak

Interesting.

My 81 US had an 089 on it and I replaced with a new 090 in about 2002.

Maybe it was the "hot" setup in the 80's to replace the 090 with the 089 given a touch richer.

The 089 WUR is the ROW WUR and , unlike the US model, it controls your fuel AFR by vacuum. The internals are different...no idea how that translates to operation on a US model with an o2 sensor/brick under the passenger seat.

[tirwin]

Good job.

So for 1.5 bar @ 16°C you are off. Consider the midpoint at 16°C is ~1.9 bar. You are off by .4 which is ~20%.

There is little margin for error according to the chart. The scale of the Y-axis is in .1 bar increments and the scale of the X-axis is in 2° increments.

Objectively, we’re left to conclude that 1) the CCP is not correct, but is not the problem (or contributing to your problem) or that 2) the CCP is not correct and is the problem (or contributing to it.)

You said your idle AFR was set by the engine builder by feel. To me that makes it unknown. Yes, you can be too rich on cold start in theory. Are you? Not enough data to draw a conclusion. We only know 1 variable (WUR) is not in spec.

If #1, then we’re back to square 1 and there is some other issue not yet identified. Troubleshooting continues.

If #2, send the WUR back to company for recalibration under warranty.

If you rule out all other possibilities then you’re left with #2 and unknown idle AFR.

[pmead]

I am going to try find a CO meter to rule out the idle mixture unknown. If I still have the problem I will wait for crappy winter weather and send back the WUR for calibration. (I don't want the car to be down during great driving weather this fall.)
Drove car to work this morning and had no stall on the 1st start. The rpms did drop to 400 and then rise to 1400 drop again and then settled at 1400 for 2 minutes before settling in at 900. I could see a 20% error causing this minor issue.

[pmead]

Just spoke with Larry at CISFLOWTECH. He said that my low cold control pressures may very well be the cause of my poor 1st cold start. (20% error is enough) He will "tweek" it and send it back.

[Bob Kontak]

Thanks Tony and Reiver. Quite a difference in the two WUR's.

Hope this works, pmead. Let us know.

[pmead]

Thanks everyone! I will post the results. Hopefully the cure will be that easy

[pmead]

I am an idiot. Last night I was going to remove the WUR to send back to Flowtech, and I started to think about anything else that could be the problem. I have not checked the timing since I got car back from engine rebuild. Went for a drive to warm it up and checked timing. 5 degrees ATDC I reset @ 5 BTDC reset idle to 900 and went for ride to listen for pinging etc.... car ran great. (I am amazed how well it ran with retarded timing before) My timing light hates the MSD ignition and gets erratic at high rpms so I could not accurately test total timing advance, but I had this dizzy rebuilt by Barry Hershon and I know that it tops out at 32 when set at 5BTDC. (distributor is now 100% mechanical advance)
Did a cold start today (65f) and car had no rpm drop, no surge, no bad behavior at all. RPMs immediately went to 1600 and slowly dropped to 900. I will do a cold start again tomorrow am to verify, but I think I found the problem. I feel real stupid but I hope someone else can learn from this thread. Don't assume anything. Check basics 1st. etc....... Again thanks to all that have assisted!!!

[tirwin]

Well, lesson learned. Glad you came back to report your findings.

[Bob Kontak]

Your car is running better. Super. Tells you it ain't really screwed up.

Take this opportunity with Flowtech to get the WUR dialed in. You don't need THAT rich.

[pmead]

Thanks Bob, When weather gets real crappy (salt on roads) I will send it back. Larry at CISFLOWTECH seems to be a straight up guy.