hi there...I need some serious advice on how to take a system test and check everything on my E4ME....

I have a 87 Camaro SC with a 305 stock engine on it...I overhauled the carb some weeks ago and mounted it back again but my earlier problems seems to still be there...

My symtoms are easy:

1. Choke not adjusted: Idles very eratically when cold....Have tried to adjust fast idle, and it was a little bit better but far away from good...

The engine idles also eratically when hot but in a different way...
Normal RPM in Park should be around 750RPM right??....And most of the time it is about 750 but goes a little bit up to 900 and almost 1000rpm and down to 600rpm...So very erratically....

I am very new to this with the CCC system so I am not sure how to test everything exept the standard diagnosic test in the Terminal inside the car and look for trouble coded.. (I don't have any trouble code)

I also bought myself a dwell-meter to check the dwell degrees on the car...And this is definately my beginning period when it comes to that...
Tried to check my dwell today, and connected the dwell-meter to the green clip on the wiring harness to the M/C solenoid and it stands on 5 degrees...not moving up and down at all...Is this right???...
I tried to block the carburettor air horn and then the dwelling moves far up...
So this means that the carb is in close position...
I really need some tips on how to do this...

Can somebody please tell me what to do??..

 

NAF Posted this in another thread should help:

https://www.thirdgen.org/forums/carb...ms-please.html

Is the Check Engine Light on? Couldn't hurt to check sensors as well, i.e. O2, TPS, MAP, etc.

 

Before you do anything...

Find the vacuum leak.

The CCC system has, what seems like, at least 18' of vacuum line ranging from 3/64" to 3/8"... Most of it being 1/4" If you haven't already REPLACE IT ALL!

Once you are sure there is no vacuum leak, double check the common things like the plugs, the cap/rotor and the wires... If any of them look the least bit suspicious replace them all too. While you are at it check that the timing is set per factory specs too.

Once that's done. Then turn your attention to the CCC system itself.

If its not issuing a code I would continue to look for something else wrong, other then a sensor, things like an EGR valve failure, AIR diverter valve failure, EFE valve failure, vacuum leak at the carb base, at the throttle bushings?

Any of these could cause a lousy idle. My bet EGR.

Simple things like a plugged fuel filter, a plugged cat or a TPS set out of whack can also have you scratching your head. Though these problems usually appear at higher RPM not idle.

 

https://www.thirdgen.org/forums/carb...e-rebuild.html
Straight from the horse's mouth.

You did have the dwell meter set on 6 cylinder, right?

 

yes...I tried everything on that dwell meter...Actually it is a Engine Analyzer from Craftsman tools...That has everything about RPM...Dwell...Voltage and so on...

I tried both 6 sylinder and 8 sylinder...But the dwell was standing straight on about 6degrees....When i put my hand over the air horn on the carb the dwell incresed a lot....

But this degrees should va right??...Like a pulse or something...Concluded to the Haynes manual it should do this....
I only have one green clip that is free from the M/C wiring harness so that must definately be that....

ur7x say I have a vacuum leak...Are you sure??...I guess this is causing the poor idle but it is also weard that the CCC-system don't show any codes...
The "Service Engine Soon" light have never came on the last half year...

After I took a overhaul couple of months ago I kept everything that has rivet's in it stay as it was...The only thing I adjusted from there was the Lean mixture screw and that is adjusted again...Every other thing should be as factory adjusted....

But i don't understand this with the dwell meter....Anyone that has an idea???

 

No, without seeing or hearing the car the best we can do is guess...
Did it run better when you covered the horn? If it did... It even more likely that you have a vacuum leak. The reason I threw it out there is because... There are miles of tiny rubber hose on these cars and one small hole can cause a world of problems... As well vacuum hose is CHEAP and EASY to replace... Since we are only guessing... why not start with an easy $10 fix vs a difficult $250 fix.

Regarding codes. OBD systems use redundant sensors and computer logic to trigger codes... On the CCC system there aren't any redundant sensors and the computer is state of the art circa 1981! While the CCC will issue codes if a sensor completely craps out or starts to act really odd... Do not rely on the code system on these cars... Or another way a lack of codes doesn't mean everything is A-OK.

But then again my ODBII Cadillac is a wash with sensors and even that car didn't issue a code when a crank sensor took a dirt nap.

 

If I understand you correctly, the dwell meter shows full-rich (meter pegged to the left near 5/10 degrees and doesn't waiver) until you choke the airhorn causing the dwell to increase? If this is the case, it indicates that the ccc-qjet and associated sensors are working correctly but the carb is not properly adjusted. Two most likely cases:

1) You've got a vacuum leak and the dwell is responding (correctly) by richening the mixture (low dwell) to compensate.

2) Upon your rebuild you didn't get EVERYTHING back to original settings.

This affects your cold start and warm-up operation because during start up, prior to reaching a warm engine temp reading from the temp sensor, the carb reverts to a warm up mode and doesn't look at O2 readings to adjust the mixture (actually O2 sensor needs to warm up too).

I'd check EVERYTHING for a vacuum leak, plug EVERY port at the carb with a cap. With the engine warm and the dwell meter hooked up, reconnect each line, one at a time, to see if any affect dwell. The dwell will respond to a vacuum leak by decreasing (rod down in jet less time=more fuel).

Once you find/fix a vacuum leak or eliminate it as a possibility you may need to fine tune either the IAB (top of airhorn...is the cover still riveted on?) and/or the idle mixture screws to bring the warm running dwell into the 45-55% (or 25-35 degree) range - middle of six cylinder scale.

When properly operating in feedback mode the dwell should constantly 'roam' and vary a few degrees each way as the ecm receives feedback from the O2.

 

Thanks for the easy explanation naf...You are understanding this right...
I am not sure if I am plugging the dwell meter to the correct cable but it is green and comes from the M/C solenoid wireing harness...There are no free cables on any harness so it must be that...

First I just connect my dwellmeter to the green clip on car..Nothings happens..When I connect dwell-meter ground to the "ground" nothing is happening..But when I connect the red wire (+) on dwellmeter and negative wire (-) on dwell meter to ground and also the green clip cable the dwellmeter shows about 5degrees....Is this right??...

Here is a picture of my dwellmeter:



I will try to check after some vacuum leaks...It could be something with that yes

I have not removed the rivets from the IAB valve...So that one is still factory adjusted...The same with the mixture needles...

 

If dwell increased when you choked the air horn, the meter's connected properly.

Even though you left most of the settings alone, you had to remove and re-install the lean stop screw. Being a little off here, or even different thickness gaskets, could be enough to require adjustment of the IAB. You're not far off though if you got the dwell to respond by choking.

Rule out the vacuum leak then pop the rivets on the IAB screw.

 

Ok...thanks..I will try that today....What is the easiest way to find a vacuum leak you say??....To disconnect the hoses and connect the dwell-meter and then connect each line and look if dwell-rod is decreasing??...
If I remember right from last time i hooked up dwell-meter the rod was standing at 5degress the whole time..If i changed the sylinder range the degrees waries...But that is just a normal calculating progress if I'm not wrong...

Ok...so then I will drill out the rivets on the IAB valve...
If I don't get a good dwell even with the IAB valve checked and vacuum leaks checked could it then be the mixture needles??..
they are also riveted so they are also factory adjusted...

 

I like to remove each vacuum line then plug the port with a vacuum cap. You can get a set of plastic caps at a parts store. A quick check can be done by crimping each vacuum line near the carb with pliers to close it off then see how dwell responds.

If you've got a leak in one of your lines you should notice an increase in dwell once they're all removed and the ports are capped. Hooking them up one at a time then will show you which one was leaking. You'll have to allow about a minute with each check to allow dwell to respond to any change in mixture.

If you find a leak and fix it and the warm idle dwell waivers around 50% (or 30 degrees) then you won't need to adjust the IAB.

Dwell meter should be set to the six cylinder scale.

Since you got the dwell to respond by choking the carb, I don't think you'll need to adjust the idle mixture screws. Check for vacuum leaks first though.

I hope I'm not being too redundant, I just want to make sure nothing is 'lost in translation'. Good luck.

 

Hey there naf...It's me again...I've just adjusted my carb again and now the dwell-meters varies about 25 - 33 degress on the 6th sylinder scale...
I think my carb was WAY out of adjustment...

I connected the dwellmeter as you said..Grounded the diagnostic terminal inside the car and start looking for vacuum leaks..The only one I found was the hose that I have taken out of the air-filter box..
Think that is the hose that is going from the Air-Temp sensor inside the air-filter box...

After I plugged that one the dwell-meter raised to about 15 degrees and varied to almost 20....

I drilled out the rivets on the IAB valve and started to adjust...The dwell was increasing so I had to turn the IAB valve 2 whole turns around...I thought that was much, but know my car idles nice about 750RPM and dwell shows about 25 - 33 degress...Varies around there...

I tried to kick the pedal a little also after I have adjusted and the engine seems MUCH nicer...The RPM is stabilizing much faster without this rough idling...

I'm gonna take my car for a little trip now to see if it has some effect after driving for a while...

Now the only problem left on my carb is my fu---- choke...lol

Very high RPM when starting...I guess i also need some special tools to adjust my choke or???

 

Did you bush the throttle shaft when you rebuilt the carb? If not I'd bet money that's where your leak is. Spray some carb cleaner or something flammable at the throttle shaft on the out side of the carb with the engine running. If the idle changes then you have found your leak. That would be the first place I'd look.

 

Good deal. Two turns isn't too much and you weren't too far off if you got the dwell to respond without having to play with the mixture screws.

There's a write up somewhere on adjusting your choke without having to use the 'bubble-level, degree tool' (don't recall exact name). It used drill bit sizes (diameters) to set choke blade gaps, IIRC.

I thought I had a copy on my computer but couldn't find it the other day. Maybe a search or someone will chime in?

When I have more time I'll look for it again.