Bosch #0 438 140 045 CIS Control Pressure Graph - Comments?

[ago85carrera]

I have a 1980 3.0 stock ROW SC with a newly rebuilt WUR and distributor and measured fuel pressures for anyone's comment. What do you think of these pressures with respect to Bosch spec for the 045 WUR (Bar is my control pressure, refBar are the spec range from Bosch manuals)? Are these control pressures what your well-running 045 WUR produces? If you have any other model WUR, how does your control pressure match Bosch spec at cold, warm, and in between? My system pressure is 4.8 bar at 9 C and control pressures are recorded every 30 seconds from CCP until it stopped rising around 9 minutes. The factory spec shows a linear increase from CCP to WCP. Does your control pressure increase linearly over time and does it stay in factory spec range between cold and warm?



That bit of nerdiness aside, I'm open to suggestions on my overall situation. I haven't been able to get the car to idle the base mix method in the Porsche factory manual (fires but doesn't start) so I did the ShopVac positive pressure test for vacuum leaks with soapy water (search "Finding CIS vacuum leaks - the vacuum cleaner pressure test"). It's a very slick method but I can't say I ruled out airbox leaks on the cylinder 4-5-6 side since I can't see between the airbox and intake runner. That being the case I pulled vacuum through the same setup to see if smoke would get pulled into the the darkness of the 4-5-6 side and smoke was not pulled in. The car REALLY doesn't want to start (fires a little when cranking but no more) at the base AFR +/- two full turns at 1/4-turn increments so what would you do? Would you still suspect a vacuum leak and pull off the airbox to inspect its underside? I'm inclined to trust the soap/smoke testing result thinking that any leaks I missed are too small to create a no-start condition.

Other tests done per Jim's Basement Garage website and CIS for Dummies thread:

• Thermotime switch tested
• CSV squirts and doesn't drip
• AAR is open when cold
• AAV not tested because it's hard to reach (I don't think it's leaking vacuum)
• Injectors flow well and don't drip
• Intake boot between flow meter and TB isn't split

I plan to check the plugs for fouling and weak spark and install a remote starter so I can crank the car with my hand moving the meter plate. Where would you look next?

I have starter fluid for my Briggs and Stratton engines but haven't used it on the car having read it's bad for FI systems. Is that myth or fact?

[T77911S]

first you are over thinking or over analyzing your problem with charts and graphs.

second, make sure I am clear on your results.
NO VAC,
CCP 1bar
WCP 2.8

W VAC
CCP 1.4
WCP 3.5 (maybe 6)

3rd I dotn think your chart is right. again over thinking it and its hard to read.
the spec I have for the 045 is:
W VAC- 3.2 to 3.6

so based on that your WCP is in spec.

tony will probably disagree with me on this as all I really care about is CCP and WCP, I think he likes to see the warmup process in spec. I would not worry about it. the WUR is very crude and basic device

for starting you don't have any vac on the WUR so look at that spec for your CCP. its tad out but then again, I would not be too concerned, its better to be rich when starting, especially if you live in the cold. for my 77 with a 033 my CCP was .8 with no vac.

it sounds like your FP is only running when cranking.
could also be mixture setting.

remove the connector on the top rear of the AFM, turn the key on and verify pump runs.
when cranking, lift or pull down on the senor plate to control the mixture when cranking.
if you have to push up to keep it running, your are too lean, or you have an air leak.

[porschyard]

if it fires on initial crank and actually starts but then dies i would try to manually manipulate air flow sensor plate (lift up) too get it to start and run sounds like base mixture is way off. it sounds like it is only starting on the cold start valve, you will have to get a second person or remote starter switch to crank engine and then catch it by lifting sensor plate to keep it running and then be ready with tool in hand to start adjusting mixture until it will run without holding up plate. i agree with t77 that you are overthinking this , it would have to be one helluva intake leak for it not to be able to run on its own. i just finished a complete cis overhual and changeover that some one put a small tube lambda ( 80-83 ) on a 79 big tube motor without brain, wire harness, or frequency valve operable, needless to say car ran terrible.as far as intake leaks you really need a smoke machine they are INVALUABLE, but also pricey .i think you can make one look on youtube for video.i have included a couple of pics ,hope this info helps richard
[img]http://fo

[boyt911sc]

ago85,

You can not compare apples to oranges. The low and high reference charts you have are cold control fuel pressures at different ambient temperatures. Your CCP- WCP fuel pressure chart/s are not ambient temperature condition. You can not compare these data because they were measured at totally different set of conditions.

Your WUR-045 is taking too much time to get from CCP to WCP. Nine (9) mins. is too long compared to the normal heating time to get to WCP. That is approximately more than twice the rate of a typical WUR-045. What is the heater resistance (Ohms) of your WUR? However, the WCP without/with vacuum are within spec.

If you have 25~26 Ohms value for the heater, then your problem is the bi-metallic spring. I call this defect “lethargic” due to some sort of metal fatigue and should not be a problem at all.

Tony