Did my pressure tests! Now, help me interpret (Calling Tim I. and Tony D!)

[garment]

Hi All - after some issues with the pressure test kit I purchased some weeks ago, I think I've got a good set of readings from my '83SC. Using Tim I's (tirwin) excellent guide and Tony D.'s (boyt911sc) ever-present inspiration on all things CIS on this board, I present the following for your review and analysis:

1. Year of engine: '83
2. US or RoW (Rest of World): US
3. WUR model number: 090
4. Ambient temperature at time of test (in degrees C): 29
5. WUR Resistance (in Ohms): 25.7
6. System Pressure (in bars):4.5
7. Cold Control Pressure (in bars): 1.30
8. Warm Control Pressure (in bars): 3.80
9. Time delta for Cold -> Warm Control Pressure (in minutes & seconds):4 min 30 sec
10. Residual Pressure @ 5 min (in bars): 1.80
11. Residual Pressure @ 15 min (in bars): 1.55
12. Residual Pressure @ 30 min (in bars): 1.50
13. Residual Pressure @ 60 min (in bars): 1.35

I've had some warm start issues this season which I'd REALLY like to solve; I've not had any tuning done to the CIS since about this time last year. I also get some intermittent idle surging on cold start.

I've got a new fuel accumulator standing by if the collective wisdom of this board says it's needed, but (per Tony D.) - check pressures and diagnose before changing out parts! My fuel filter is relatively new (installed 1 year and 3,800 miles ago)

Thanks for your help Pelicans!

[tirwin]

WUR resistance is good.

System pressure is on the low end of normal. (4.5 - 5.2 bar)

Cold control pressure at 29° C should be between 2.6 - 3.0 bar per the Bentley.

Warm control pressure is on the high end of normal (3.4 - 3.8 bar).

Warm up time is fine.

Residual pressure is fine.

Can you describe the warm start problem?

[garment]

Thanks for reviewing the numbers. If cold control pressure is out of spec, what is the recommended action?

On warm start engine will catch after 3-4 cranks. Car will idle but low maybe 500 RPM, and almost dies without giving some gas. Hesitates the beer any lod for 10-15 min of driving, then settles in. Does this tell you anything?

[tirwin]

Low cold control pressure means an overly rich mixture on cold start. As control pressure gets lower, the fuel mixture gets richer and vice versa. The WUR will have to be adjusted.

Tony has posted a method to test the fuel accumulator. Do a search with those words under his username and it should come up. Do the test and you can either replace it or you'll have peace of mind that it's not the culprit.

Idle surging on cold start and warm start problems have some common causes. 1) vacuum leaks 2) leaking cold start injector 3) leaking fuel injectors/uneven fuel spray and 4) improper basic idle.

Cold start injector is a bugger to replace. I'd suggest adjusting the WUR and then rule out the other 3 possible causes before tackling the cold start injector.

[garment]

So...I called two different companies that work in CIS component refurb/re-manufacture with the results of my test (they are mentioned often on this board, but I will keep them anonymous)...and got two different ideas on what to do next. Now, I am further confused...

One said WUR rebuild, per Tim's comment; also to pull the injectors (in response to my warm start trouble and low/rough idle on warm start) and have them cleaned/tested.

One said residual pressure and to swap out the accumulator, and kind of took me to task for using fuel cleaner and killing the injector o-rings (I've used BG, Seafoam, and Techron in the past, but not overly so).

Who's right? Kind of got a better feeling from respondent #1...

Thanks.

[Bob Kontak]

Originally Posted by garment

One said residual pressure and to swap out the accumulator, and kind of took me to task for using fuel cleaner and killing the injector o-rings

Tell this guy to stuff it well up into his secret place.

For one, 1.35 bar after an hour is something like 19-20 psi. You DO NOT HAVE have a residual pressure issue.

Also, techron, seafoam, muratic acid, rocket fuel, mother's milk and whatever do not come close to touching the injector O-rings on an 83.

Guy is an idiot who is blowing smoke up your butt.

[garment]

Yeah, definitely got the wrong way rub from #2; thanks for confirming!

Originally Posted by Bob Kontak

Tell this guy to stuff it well up into his secret place.

For one, 1.35 bar after an hour is something like 19-20 psi. You DO NOT HAVE have a residual pressure issue.

Also, techron, seafoam, muratic acid, rocket fuel, mother's milk and whatever do not come close to touching the injector O-rings on an 83.

Guy is an idiot who is blowing smoke up your butt.

[Bob Kontak]

Originally Posted by Bob Kontak

Guy is an idiot who is blowing smoke up your butt.

If the guy is in this forum and is known, there may be info that has not been shared or he does not have your set of data posted. Perhaps not an idiot.

Your CCP is grossly rich on start-up. Will cause your surging. Tim's CCP numbers are in line with the later US SC graph. I can post if needed.

There is a bump the plug procedure but it's been a while for me.

I am thinking some air sucking. You have the high range of WCP. Throw in false air and you double down on lean.

[T77911S]

what are the warm start issues?
as stated you do not have a residual pressure problem.

how is the ignition and timing? that has to be working great before you work on fuel issues.

have you had the mixture checked?

there are a couple of areas i am thinking about:
1. the O2 sensor. with it being a warm start issue (but not knowing what) i am wondering if it is still closed loop when you have a problem and it is pulling the mixture way off. (could just need a slight mixture adjustment or a new O2 or something with the lambda control unit).

2. with the CCP being so low is the WUR dropping the pressure low enough to cause it to be too rich when warm. what i would do here is with the gauges on and it having the hot start problem, remove power to the WUR. as soon as you get it started when warm, check the CP.
i believe the WUR can cool faster than the engine.

check the dwell of the FV when it is running and hot. i dont know if you can check it with the engine off but i would try that or either check it as soon as it starts when warm.

3. an injector problem. could be leaking.