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Rough idle/stall issue

Agreed, all of the problems seem to be fairly obvious(so far). I have always done my own maintenance and repairs, but I am new to SBC's and this is going to be the most in depth/thorough work I have done on a vehicle(which was the original idea behind buying it anyways) so I will have lots of questions over the course of my build/rebuild of this truck. Back on topic, it appears it is not the factory SBC intake manifold since I can't find anywhere for the CTS to even be installed. Im going to try to find the O2 wire and get that hooked back up and go from there. Tomorrow I will try to get some pics of what I am working with. I would get some now, but my camera takes terrible pictures in anything short of daylight, even with the flash.
 
Yep, and TBI systems are soooo simple. I swapped in a BBC and I freaked out for months trying to figure the rats nest out. Then I realized that 95% of the plugs only reach so far, and only plug into one type of plug. So I just started hooking them up, and it came together, then I redid the entire system of new looming and viola mission accomplished.

BE SURE to check the plugs for broken off snap locks, as the 2 wire and 3 wire plugs can fit in both ways, but will freak the ECM out, It took me 2 months to figure out my TPS wire was hooked in backwards........ :doah: :haha:

Now it runs like a top, and I personally love the TBI, as there is a half dozen sensors, so not too much to fail, its a very reliable system once you get all the bugs worked out.


EDIT, you can hook that CTS anywhere you want as long as it touches antifreeze, reads temp, and the wires reach. But it should go either in the t-stat housing, or the front of the intake in a pipe plug.
 
Won't be doing any more tonight. It's been raining pretty hard outside for a while so I have been making room in the garage. Will post my new discoveries as I find them.
 
And BTW, I am pretty excited about having a TBI setup for that reason. I have also read they tend to produce a little more low end grunt, which is what I will need once I get it ready for real riding. It will likely see more sand dune action than trails, but it has to be good for every day as well, since I will be driving it to work.
 
Worst case, you may have to extend the wires, but the CTS I believe will thread into the plug on the passenger side head, same spot the temp sender would be on the drivers side.
 
New developments so far: connected the O2 sensor, now I'm getting a new code- 33: High voltage(low vacuum) to MAP sensor. I don't have much time to get into it today, but I will be checking that out as soon as I can. Thanks for all the help so far guys.
 
I'd be looking at the EGR portion if it's been monkeyed with, that is a vacuum leak if it's not plugged or sealed correctly.
 
It has a vacuum port on the backside of the throttle body. It will be the only one plugged in to it. It's a small flat, 2inx4in piece with a 3 wire hookup and one vacuum port. Check to see if hose is plugged or split or unhooked even
 
The vacuum lines are all hooked up and in good condition. I think I may have triggered the code when I was checking them for good vacuum pull. Learning experience of the day: don't reset the codes until the problems are actually fixed. The truck won't start so I'm going to get the CST now to put in.
 
Correct, after you install the CTS, unhook the battery to clear codes. You will get mighty used to this unhook/hook thing. You need to do it every time you install a new sensor to clear the old ones problems out. I learned never to set radio stations (I have a aftermarket cd player and subs and blah blah) till I was dang sure it was running right.

You can test the MAP to see if it holds vacuum, I tested mine by sucking on the port and sticking my tongue over the port and seeing if it would fall off. Not the correct or GM way of doing it Im fairly certain, but it did work.
 
Update: I got the CTS installed, and it really smoothed things out. It still needs some tweaking, since it is still stalling, but definite progress. It seems like maybe the idle is a little low for the current cam. Like I said before, a pretty thorough tune-up is in order soon and I will make more adjustments from there.
 
I'll check the FP when I get a chance. Makes sense that it's low FP, which is something I have suspected as a contributing factor since I bought it. I'll be replacing the fuel filter regardless, since it looks pretty old. With a little luck that could give me the bump in pressure that I need.
 
Figured out why no EGR valve. It's not an intake from a 1 ton, but an Edelbrock Performer RPM. Designed for 1500-6500 rpm, no EGR valve, designed for high performance applications. Good to know it won't be a limiting factor for future upgrades, but my idle right now is well below the specified rpm range, do you guys that that could be part of my problem?

http://www.summitracing.com/parts/EDL-7101/
 
Not having an EGR will trip a code once the vehicle reaches a certain speed. A few things to check, on the TB, look on the throttle linkage side and see if the idle screw has been tampered with. It should have a plug of some sort over where the screw would be, preventing people with messing with it. If its been tampered with, you will have to reset the base idle, there is a procedure for all of this, but dont do it unless its been messed with. Also check the injectors for an even conical spray, easy way is in the dark with a flashlight. No dripping or dribbling.

Secondly, it may idle strange until the computer relearns all its operating ranges for the engine. You should do, if you havent already, is do a tuneup, plugs, wires, cap, rotor, and fuel filter. Once you have it running right, with no codes, then you can start to diagnose the little things.

And further thinking, you can turn your factory FP regulator into adjustable, there are links all over the internet about it, or you can buy one from Summit. You will need a gauge to accurately set the FP, I just mounted a liquid filled one on mine. Having an intake like that, plus a cam, I would almost bet its going to lean out across the board. You probably need to up the FP a lil bit, to around 13 or so. And in the long run, to get it 100%, your going to need a custom burned chip from www.tbichips.com
 
I plan on doing exactly the tuneup you described soon(when the budget permits) and hopefully that will help with some of the issues. I also plan on an adjustable fuel pressure regulator(most likely a DIY setup on the stock one) and an oil filled in-line pressure gauge. I haven't even had the truck a week yet and have learned quite a bit. I'm almost thankful in a way that the previous own did sloppy work, since it has given me some good learning opportunities. Once I get the idle issue figured out I will look into a custom chip. I don't know what cam is in it, or what else is aftermarket, so I will have to do some digging to get a good tune. tbichips.com looks like a good option for that. Thanks.
 
If the intake and cam have been changed, you probably need to do the "minimum air" or IAC adjustment as I believe it's also called.

You REALLY have to make sure that everything else is up to par before doing it, but I spent a fair bit of time trying to figure out the stalling on decel issue on my Dad's TBI setup before I realized the PO of his injection setup had tried to adjust idle, and obviously did so the wrong way.
 
Get the TunerPro RT and cable for your laptop, record some data and we can look at what it needs. May as well get a chip tuned for your motor.

This is after you have mechanical issues resolved.
 
454sub, do you know any links to instructions on converting the fuel pressure regulator to adjustable? I don't mean to sound lazy, I have checked on google and all I can find are adjustable units for sale. Also, where would be the best place to mount the pressure gauge? I have read that mounting them in the engine bay can screw up an oil filled gauge. Thanks.
 
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