y5mgisi
1 ton status
I havent checked with a gauge yet. But based on data logs, its better by around 10kpa or so. Gotta find my dang miss!
CK5
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Thinking of doing the unthinkable... *Rotor to cap gap. Normal?*
- Thread starter y5mgisi
- Start date
10 kPa is about 3 inHg
y5mgisi
1 ton status
Any input on running autolite 25's or 26's? 25's are the recommended ones, but it seems like a good idea to run the 26's again.
y5mgisi
1 ton status
And the new plugs did nothin. Got a couple videos coming later.
magik235
Still Alive
This thing is bugging me. Why don't you drive it to central Wisconsin. I want to look at it in person. 
y5mgisi
1 ton status
I wish! Stupid thing.
y5mgisi
1 ton status
My couple vids of the crapper,
And the injector patern,
[YOUTUBE]7LotFWuoL-U[/YOUTUBE]
And the injector patern,
[YOUTUBE]7LotFWuoL-U[/YOUTUBE]
Last edited by a moderator:
what's the injector history? look at the pattern with a timing light flash, you'll see the pattern better...
sorry, i haven't read thru the thread, what's it's current issues?
sorry, i haven't read thru the thread, what's it's current issues?
y5mgisi
1 ton status
Low vaccum, max rich, running rough. Injector history is i had them rebuilt and flow matched when this all started some 5 years ago. Sense then i have put about 10k miles on the truck. I have donw the timing light thing and its tough to really see the pattern. I definitely dont see any kind of cone.
Dude, I think it may be time to call it quits and just get a new engine for the truck! I don't know about your area, but TBI 350s are pretty much given away around here these days (everyone wants a Gen III engine)!
That said, my final recommendations would be to check:
- Fuel pressure. Make sure it is 12 - 15 PSI on the inlet. Make sure that it doesn't drop below that range under load.
- Distributor. Make sure the shaft isn't worn, that the magnetic pickup is good. Make sure your plug wires are good and that the plugs are gapped properly. Ensure the coil delivers a sharp blue spark, not a reddish / fuzzy spark. Make sure that the timing is steady and that all the plug wires are good. Also confirm the firing order, I've messed it up many, many times myself.
- Make sure the throttle body itself is in good shape. I have seen a ton of them with worn out bushings on the throttle shaft (major vacuum leak!)
- Make sure that minimum air is set correctly (see my post from a couple years ago)
- Make sure that the cam profile and heads are similar to a stock TBI engine. Mass air engines don't adapt well to engine changes.
- Make sure the valve lash is set properly.
From the looks of it, you've changed practically everything else on the engine. I think it is probably still a mechanical or timing problem.
Again, you can buy TBI 350 engines really cheap! Be worth the $500 IMO
That said, my final recommendations would be to check:
- Fuel pressure. Make sure it is 12 - 15 PSI on the inlet. Make sure that it doesn't drop below that range under load.
- Distributor. Make sure the shaft isn't worn, that the magnetic pickup is good. Make sure your plug wires are good and that the plugs are gapped properly. Ensure the coil delivers a sharp blue spark, not a reddish / fuzzy spark. Make sure that the timing is steady and that all the plug wires are good. Also confirm the firing order, I've messed it up many, many times myself.
- Make sure the throttle body itself is in good shape. I have seen a ton of them with worn out bushings on the throttle shaft (major vacuum leak!)
- Make sure that minimum air is set correctly (see my post from a couple years ago)
- Make sure that the cam profile and heads are similar to a stock TBI engine. Mass air engines don't adapt well to engine changes.
- Make sure the valve lash is set properly.
From the looks of it, you've changed practically everything else on the engine. I think it is probably still a mechanical or timing problem.
Again, you can buy TBI 350 engines really cheap! Be worth the $500 IMO
y5mgisi
1 ton status
Stupid motor. 5 damn years worth...
y5mgisi: If it makes you feel any better this thread reads identical to what my truck has been doing to me for about 5 years too. I finally had a carb set up fall in my lap for dirt cheap and when I get it on(week or 2 till I get to it) I will def let you know how it worked out. If it cures my problems maybe we can get together and start a big TBI fire and dance around worshiping the Carb gods for relieving our massive head aches
.
.I remembered that my neighbors '90 454 TBI was acting up. Mechanics couldn't pinpoint what was happening, I got involved, and I couldn't figure out the TBI stuff at the time.
He eventually sold it, and a mechanic I knew bought it. Turns out the computer was bad. It was telling the motor to do all sorts of random crazy stuff, including stalling and not restarting a few times. He put a used computer in it, and it was back to it's old self.
He eventually sold it, and a mechanic I knew bought it. Turns out the computer was bad. It was telling the motor to do all sorts of random crazy stuff, including stalling and not restarting a few times. He put a used computer in it, and it was back to it's old self.
This is a huge thread, and I have been in it for a while, maybe from the beginning, so a lot of stuff gets missed.
But he changed computers out a long time ago with no results.
Problem is, I'm afraid that some of the stuff he tried before might have helped or cured what he has now but it was masked by the cam problem.
I'm looking forward to the next time he pulls the plugs. He had one that was almost certainly not firing.
Now it seems to be running rich, which could be caused by a misfire making it look rich due to unburned fuel.
I really think he has fixed the main problem at this point by adjusting the cam. We almost need to start from scratch and ignore past problems and look at this as a new problem.
If its firing on all cylinders now, and still rich, then we need to look at fuel pressure and injectors again as has been suggested.
Something may have gone wrong since he last did that.
And, if those are good, then a temp swap of the computer again might be in order.
But he changed computers out a long time ago with no results.
Problem is, I'm afraid that some of the stuff he tried before might have helped or cured what he has now but it was masked by the cam problem.
I'm looking forward to the next time he pulls the plugs. He had one that was almost certainly not firing.
Now it seems to be running rich, which could be caused by a misfire making it look rich due to unburned fuel.
I really think he has fixed the main problem at this point by adjusting the cam. We almost need to start from scratch and ignore past problems and look at this as a new problem.
If its firing on all cylinders now, and still rich, then we need to look at fuel pressure and injectors again as has been suggested.
Something may have gone wrong since he last did that.
And, if those are good, then a temp swap of the computer again might be in order.
It is a longgg thread. 
I forgot about the computer, and the cam timing certainly was necessary. No engine will run well with too low of cylinder pressure.
If it's one plug not firing, then that is a good focused problem to work on. Years ago I had my own tuning shop (carbs and distributors, for those who remember them). But without my eyes and ears working on it, I'm not too helpful across the internet.
When it's finally discovered, what a huge help it will be for the next person.
I forgot about the computer, and the cam timing certainly was necessary. No engine will run well with too low of cylinder pressure.
If it's one plug not firing, then that is a good focused problem to work on. Years ago I had my own tuning shop (carbs and distributors, for those who remember them). But without my eyes and ears working on it, I'm not too helpful across the internet.
When it's finally discovered, what a huge help it will be for the next person.
I agree, doesn't look like it's been working. But from my keyboard I don't have any good input. I've had a few HEI distributors that had a bad reluctor wheel, or whatver it's called, where one plug wouldn't fire.
If it was too rich to fire, you would smell it in the oil. But it's tough to be too rich to fire unless it was a middle plug. The plugs on the end run leaner.
I was watching the end of the youtube, I couldn't hear the miss through computer speakers, but I can see the miss in the exhaust. It's already been covered, but my input would be ignition related first, then check if it's too lean (possibly borrow an infrared gun to measure the temps at each exhaust port, does it ping under heavy throttle on regular gas, vacuum leak, ?).
Sorry, not much useful input today.
If it was too rich to fire, you would smell it in the oil. But it's tough to be too rich to fire unless it was a middle plug. The plugs on the end run leaner.
I was watching the end of the youtube, I couldn't hear the miss through computer speakers, but I can see the miss in the exhaust. It's already been covered, but my input would be ignition related first, then check if it's too lean (possibly borrow an infrared gun to measure the temps at each exhaust port, does it ping under heavy throttle on regular gas, vacuum leak, ?).
Sorry, not much useful input today.
Pinsco63
Registered Member
stupid question
I don't know if you mentioned it, but when it was running did you pull plug wires until you found cyl that had no change? Thought of that last night but forgot to ask. It might help to at least know what hole is the problem. I know the chances are you have but just trying to think simple instead of confusing our selfs with jumping all over the place. If you did mention it sorry this thread and problem is too long for me to go over it again and with very little pics I loose interest.
I don't know if you mentioned it, but when it was running did you pull plug wires until you found cyl that had no change? Thought of that last night but forgot to ask. It might help to at least know what hole is the problem. I know the chances are you have but just trying to think simple instead of confusing our selfs with jumping all over the place. If you did mention it sorry this thread and problem is too long for me to go over it again and with very little pics I loose interest.
y5mgisi
1 ton status
y5mgisi: If it makes you feel any better this thread reads identical to what my truck has been doing to me for about 5 years too. I finally had a carb set up fall in my lap for dirt cheap and when I get it on(week or 2 till I get to it) I will def let you know how it worked out. If it cures my problems maybe we can get together and start a big TBI fire and dance around worshiping the Carb gods for relieving our massive head aches
Sounds good to me!
Now how do i multi quote?!
y5mgisi
1 ton status
Yep, computer has been replaced and then replaced again with a junkyard one when i wasnt convinced the reman unit was any good.
Thats what im hoping for!
Nope. Never has.
This i would like to do! Just need to either break down and buy one or find Someone with one i can borrow.
All i did was the test light thing. Where you ground the clip end of the test light and probe the wires at the cap to ground them. When i did that there were several that made almost no difference, several that made i slightly noticeable difference, and several that made a big difference! So that test was in conclusive.
