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Old 09-07-2008, 10:17 PM   #1
DPG1983
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Default Cold Start and Idle. B21FT

Hey there guys and gals, I am quite new here and just got a few problems to sort out with the old beast.

Specs.
1983 242GLT
B21FT w/ Intercooler. (Runs CIS)

Anyways, I have a cold start issue and some insight would be helpful.

The car has a hard time starting when cold, which means I gotta really crank it while giving it gas. Eventually it will catch and I have to keep the revs up in order for the car to not stall. If I let off the gas and try to make the car idle it will car stall.

If I keep the revs up for about 2-3 minutes and then let the car idle, it will idle at 900RPM. When the car gets to normal operating temps it idles at 1500RPM.

So the first thing on my mind was maybe the cold start injector wasn't injecting. So I tested it, and it turns out that the injector is firing in spurts. Like it's timed, but being a CIS (or K-Jetronic) I would assume the fuel coming out of the injector should be constant?

I guess I should tell you now, that I think I am getting some serious blow by. On account of there was oil throughout the intake system including air filter. I have since taken it all apart and cleaned it all, including the throttle body.

After that, can anyone tell me a way to test some other components of the cold start system? Or maybe some other possibilities/solutions to my cold idle/start problems?

P.S.
I was about to do a compression test, but I don't have the right size spark plug socket. So I have to go pick that up tomorrow. If you want you are allowed to tell me the size I need.

Thanks for any help! Cheers!

-Dan
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Old 09-07-2008, 11:55 PM   #2
$wedish
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How does it run/start once it is warm? My car was doing the same thing, but ran good once it warmed up. It was the control pressure regulator. I would definately do that comp test too.
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Old 09-08-2008, 12:28 AM   #3
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Once it warms up, it runs pretty well. It does idle at 1500RPM at standard operational temp but that's a simple adjustment I would imagine. Other than that, Hit the gas, and she goes. Although I do get an occasional "hiccup" on hard acceleration. Also, she starts very well when hot.
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Old 09-08-2008, 04:28 AM   #4
Coupe' de Grace
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Dont confuse yourself and everyone else, k-jet = constant injection but does not = CIS constant idle system, a separate subsystem for keeping a steady idle.

start by checking your TPS operation, make sure it operates electrically when the throttle closes.
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Old 09-08-2008, 12:24 PM   #5
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The starting behavior indicates an intake leak, the high idle could also be caused by that. Odds are there is a leak somewhere between the air flow sensor and the clyinder head.
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Old 09-08-2008, 07:40 PM   #6
DPG1983
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Hummm...

So for my next steps I shall remove the intake manifold and TB to re-gasket and search for leaks. And do my best to clean out the WUR to see if it makes a difference. At least I got a place to start now.

Thanks guys!
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Old 09-08-2008, 08:55 PM   #7
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Yeah I chased that same problem for weeks. Checking for intake leaks is free so why not try that first. I would do just like you said and try to clean that WUR, if that dosent work swap one from you local junkyard. I paid $15 for mine and after i put it on, it fired on the first try with no foot on the pedal and idled like it should. That was after I checked/changed everything else including the cold start injector, auxillary air valve, replaced all vacuum lines, fuel pumps/relay and more.
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Old 09-08-2008, 10:49 PM   #8
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So, I just removed the WUR and guess what I found after taking it apart? Alot of white "carbonish" build up, not really sure what it is. Along with it I found rust and other loose peice of garbage kicking around. What I'm trying to do right now is get the filter out so I can clean it thoroughly but I don't think that is possible. Unless I am told otherwise. So I will clean it as good as I can, put it back together and let you know how it runs.

I also did a comp check, and it as as follows: (Front of car to rear of car, in terms of Cyl #)

Cyl 1 : 135
Cyl 2 : 120
Cyl 3 : 125
Cyl 4 : 140

With a 7.5:1 comp ratio for the engine (I assume it's stock) what should the PSI be? Saying that, they are all within 15% of each other, so I think I can hold off on a engine rebuild for the time being. Unless of course it suppose to be like... 180PSI.

Thanks for all the help so far!
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Old 09-09-2008, 01:33 AM   #9
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your compression sounds OK to me.

In addition to the checks for intake vacuum leaks, now is the time to clean the PCV system - including the box mounted on the side of the block under the intake mani. It can be removed without taking the manifold off, but seems like lots of folks like to do the intake mani gasket at the same time.

After the PCV clean-up, I'd be checking to confirm your CIS system is working. Does the throttle position switch click when rotated to idle position? Is the idle air motor (again under the intake mani) humming at idle?

I don't believe that "giving it gas" with the accel pedal is doing anything for you when starting but I might be wrong
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Old 09-09-2008, 07:07 PM   #10
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Cleaned the PCV system already, including that black box. Will continue to do the other checks today or tomorrow. And let you know what I get.

Also I just assume having the pedal down while starting gives it some gas once it catches, so it doesn't just die on me right away. Although I hate seeing it go to 3k rpm when its nice and cold.

Gotta go throw a new starter in for my brother... Nissans are a pain in the ass.
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Old 09-10-2008, 07:51 PM   #11
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So, I got my old WUR in, all cleaned up. And now it doesn't seem she wants to start at all... After about 5 minutes of trying anyways.

I have found no vacuum leaks, and that includes me taking off all the hoses and checking them. So unless it's the intake manifold gasket or TB gasket I don't think I have any vacuum leaks. But I will be changing those this weekend.

Without being able to start the car, is there any other way I can test the idle air motor?

For now, I will pick up a new/used WUR and get those gaskets done.

Quick question here, the cold start injector is supposed to fire timed right? Like once every second or so?
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Old 09-10-2008, 08:18 PM   #12
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Yes, the cold start injector when activated by the thermal time switch is pulsed by the relay that is next to the ignition box. It's supposed to do what you saw.

Don't take this the wrong way. You are working on a kjet injected engine. You need to rent or buy or build a kjet fuel system pressure tester. You need to check the control pressure, main system pressure and the rest pressure so you know your kjet is functioning properly. There are no work arounds. You need to get the right tool for this job because this system operates off of pressure to provide the correct fuel mixture from warming up to a fully warmed up engine. The control pressure regulators job is that and you want to watch the whole process from cold engine startup to fully warmed up so you see what the control pressure does.

Once you know the mechanical parts of the system are operating properly. You can move on to checking the electrical parts like boost enrichment, operating dwell, and so forth.
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Old 09-10-2008, 08:31 PM   #13
DPG1983
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Defiantly not taken the wrong way over here, no worries.

Like it is said, it is better to do things the hard way then the wrong way.

So, with that stated I'm going to pick up a fuel pressure tester with all the required accessories tomorrow instead then. I would imagine they are pretty much all similar correct? Maybe It's time for a manual as well.

Haha anyways, that will be my next step then. I will let you know how it goes by the time Sunday rolls around. Thanks for the info. Cheers!
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Old 09-10-2008, 09:17 PM   #14
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+1 on the pressure tester, and all the pressure specs are in the greenbooks. Also I dont think our cars have a idle air motor, its more just a valve that is open when cold and closed when warmed up. As far as testing it without the engine running im not sure if you can.
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Old 09-10-2008, 09:18 PM   #15
dl242gt
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The kjet fuel tester is slightly different. It involves having a valve that lets you shut off the pressure or open it to the gauge and pass through. It's setup like a fuel line with a T off of it that goes to the gauge. The T has a valve that lets you adjust the flow for the various tests. A pressure gauge kit may but usually doesn't have the right setup for that.

The manual will be helpful but you can probably find the information you need at this site.
Genuine Volvo manuals. http://www.k-jet.org/ That's a great site setup by one of the members here. Scroll down till you see the greenbooks section link on the right side. Check out the green books and download the pdf files for all the areas you need to troubleshoot.
You'll need Adobe Acrobat Reader to view the files. Let us know how you make out and I wish you well.
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Old 09-10-2008, 09:21 PM   #16
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A B21FT has the Constant Idle System. A separate computer system that uses engine rpm, engine temperature, and throttle position to regulate the idle. Only the 1982 kjet normally aspirated used it for that one year. But all 240 turbos with B21FT used it from 81-85.

For cold control pressure you can test without the engine running. But to see the cold control pressure transition to fully warmed up pressure you run the engine with the pressure tester installed on the engine. To test and run the fuel pumps with the engine off. You jumper from fuse 7 to fuse 5. I recommend using a fused jumper lead with a 16 amp fuse in it.
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