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Thinking of doing the unthinkable... *Rotor to cap gap. Normal?*

Gotta hook these things up to a scanner, if using hardware that allows you to see the electrical input to the ECM.

Throw lots of money at a problem replacing parts, for a $10 temp sensor, and/or $100 scanner.
 
IIRC I did replace the temp sensor(the smaller comp one not the one for the guage) And i have messed around and around with minimum air setting.
 
This is pretty obvious but have you changed the fuel filter?

My truck died on me for no reason one day and would not start. replaced the fuel filter now runs great.

This can only be a couple things.
1. Fuel
2. ignition
3. vaccum leak.

For fuel I think I would check pressure and duty cycle.
For ignition I would check timing some timing guns will show you the timming (changes in timing is what I would be looking for)
for vaccuum leak I would use a can of carb cleaner.
 
i have an 89 stepside that is doing the same thing surging idle expesialy when cold and when u give it gas it back fires bad but if the truck has been siting in warm weather or the sun heats it up it still surges but not as bad and it idels really high
 
So the truck still runs awful.... I did a compression check last night. all cylinders were right about 130ish. Seems a bit low but decent? And in doing so i checked my plugs. They were all pretty black. So its running very rich.
 
Holy cow, 3 years later and you are still having trouble? You, sir, have incredible patience! :D

Did you ever hook a scanner up to the ECM to see what it is seeing? I built one of those ALDL -> Serial adapters to scan it with WinALDL not too long ago for about $15.00 ($10.00 of which was the project box I bought for it, haha)

A good data-log will tell you a lot about what is going on with your engine without you just spending money and throwing parts at the thing based on hunches.

Of course, you can always check stuff like your fuel pressure and ignition systems too. A ruptured fuel pressure regulator will make for a pretty poor running engine. Even a weak fuel pump or clogged fuel filter can cause all kinds of issues. A shorting plug wire, or bad plugs can cause all kinds of havoc with the injection system (even a bad wire that isn't necessarily shorting, but causing inductive interference on a near by signal wire!)

Do the free stuff first, then spend the money when you have cold hard evidence of a failed component rather than just wasting money tossing parts at it.
 
Fortunatly i have replaced vertualy every part on it with no change... Lets start a new list...

Replaced;
fuel pump
fuel filter
coolent sensor
02 sensor
IAC motor
TPS
MAP sensor
ignition control module
computer
coil
pcv valve
knock sensor
egr valve
throttle body complete rebuild including rebuilt flow matched injectors, FPR, and re bushed throttle shaft bores


And thats about everything... I have driven it around with a autoxray tool on it and watched things(the results are here somewhere) nothing really stood out. I had a guy from cascadecrew.org hook up his laptop to it and i forget why but we couldnt actually log but nothing seemed out of place to him. I will have to get gack into the whole data logging thing now that i have my own laptop.
 
When you rebuilt the engine, what else did you have done? Did you change the compression any? How about the rocker arm ratio?

The cam isn't ideal for EFI (114 LSA would be better), but it shouldn't make the engine run quite so poorly. Does it run better before it drops into closed loop, or does it run better after it warms up a bit?
 
I dont think the compression changed. If it did it should have been pretty minor i think? Did the tbi motors originally come with flat top pistons? Cause thats whats in there now(with valve reliefs). The rockers are stock. It pretty much runs bad all the time. I would say worse when warm but it runs bad right off the bat. Running rich. At some point its like it realizes what a bad job its doing and the check engine light will come on and it will just mostly snap out of it and idle a touch higher and quite smoother. I belive when it does this its getting itself into limp mode.
 
Your making a big assumption there, that it makes it into closed loop. Unless he actually sees it going into Closed loop with a scanner.
 
Yup, if it suddenly smartens up, it may well be going into closed loop. Have you actually tested your fuel pressure on the truck? Or are you just assuming that it is ok because you put a new regulator on? You can't make any assumptions with the basics on EFI. New parts are not always good either...

I just recently helped get an old CJ with a TBI setup swapped onto an old 305 that was originally carb, and dude was totally convinced that his ECM needed to be replaced because it ran bad all the time, lean popping and no power, running hot. Same as you, he replaced absolutely everything on that truck to try and solve it. I put a fuel pressure gauge on it and immediately found that his fuel pressure was only about 5 PSI. He had a "Brand New" fuel pump on it, but it winds up it was a brand new 6.5L turbo diesel electric lift pump on the frame rail. They are a reciprocating pump rated for 15 PSI on the side, but the average pressure is closer to 5 once you consider the reciprocating part of things.

Put a new pump in, and while it still does not run quite right due to the camshaft being kinda poor with the EFI setup, it is drivable now.
 
if its any consolation, It has ran the same threw out the new pump, filter, and pressure regulator. Back in the day i tested it and it was at something like 13 psi i think?
 
So I was just goofing around with my timing trying to iron out an idle issue i have. With the TSS(right?) wire unpluged, and the timing set at 4*It still bounces around slightly. Also with the wire un pluged, if i rev it up a little the timing goes up to around 10-12* then comes back down like a centrifigul(sp?) advance. Is that normal?
 
Take it to a mechanic. Your just over looking the problem. Ever lose your keys and look for them all day, then someone walks up and ask if you checked your pocket and there they are??? Sometimes you can just over think it is all.
 
So im starting to think that maybe the chip and the cam arent working out. What do you guys think? Would this cam work ok with a stock TBI setup?

heres cam specs
Basic Operating RPM Range: Idle-5,500 RPM
Intake Duration at 050 inch Lift: 204
Exhaust Duration at 050 inch Lift: 214
Duration at 050 inch Lift: 204 int./214 exh.
Advertised Intake Duration: 262
Advertised Exhaust Duration: 272
Advertised Duration: 262 int./272 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.420 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.442 in.
Valve Lift with Factory Rocker Arm Ratio: 0.420 int./0.442 exh. lift
Lobe Separation (degrees): 112
Intake Valve Lash: 0.000 in.
Exhaust Valve Lash: 0.000 in.
Quantity: Sold individually.

Camshaft, Hydraulic Flat Tappet, Advertised Duration 262/272, Lift .420/.442, Chevy
 
is that the edelbrock performer cam? I knew a kid that put one in his TBI 350 and it ran like a scalded dog at WOT but ran like **** otherwise.
 
That looks like pretty similar specs to a Comp Cams XE262-H... I tried running one of those with a TPI setup once, and it was an absolutely turd all around. That cam was the reason why I bailed on that engine and went diesel with my truck -- Haven't looked back since.

112 LSA is really pushing it for an EFI engine. They'd far prefer to see something closer to 114 degrees. EFI likes high lift with a short duration, snap those valves open and shut quickly, with very little if any valve overlap. Any fresh air going straight from the intake out through the exhaust is gonna wreak havoc with your oxygen sensor. I can say from experience that even a bone stock carburated engine's camshaft does not perform well with TBI, it surges at idle all the time, and tends to stall out at part throttle.

The unusual part is that the engine normally ran pretty good when it was in open loop, and would misbehave only after it warmed up and switched to closed loop, whereas yours seems to be the opposite.

If you are looking to do a cam swap, try running an Edelbrock EFI camshaft for a stock TBI truck. I installed one along with a set of headers and a Edelbrock TBI intake on a buddy's K5, and it performs really well in his K5. Made a huge difference in power over the stock engine, but still runs like stock.

Where are you running your timing at? May seem like a pretty stupid question, but you are disconnecting the EST single pin connector when adjust the timing, right?

Also, how are you setting minimum air on your truck? Have you checked to make sure that the IAC and it's passages are in good condition?
 
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