Got a new pcv valve because they’re super cheap, replaced the line from the intake to the valve, replaced the line from the egr valve to the intake. Pulled the old egr valve and it didn’t look awful but the gasket was fused to it with some rust and it’s definitely seen better days, I could have just got a new gasket but I opted for a new valve. The old one moved fine, there was some gunk inside but not bad. Couldn’t put the new pcv valve in because I bought the wrong size grommet, I’ll fire it up whenever I get the right grommet and we’ll see what happens. I’m not chasing down a vacuum leak after this, if I suspect a leak I’ll just buy a gauge and check it. I should only have to pull the radiator to get good access to the timing chain (aside from pulling the water pump and dampener of course). I calculate roughly $150 for a new chain and gear set, new gasket and seals for the cover, and a new decent dampener. The job doesn’t scare me i just want to be sure that’s what it is before I commit. Is there anything that could be going wrong in the valve train that would make it run like this? Bent rods, stuck valves, lobe wear on the cam, Loose rockers? Just trying to think it all through.
CK5
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350 TBI surging
- Thread starter Jake_C_
- Start date
Case of beer its an intake leak, either the intake gaskets or the tbi base gasket.
Replaced the tbi base gasket. Could be the intake gasket but that doesn’t explain it running very advanced right?
If it is leaking it will idle erratic or higher depending on how the computer is responding. Any vacuum leak will cause a number of problems, eliminate all of those first before you move on.
it could be a temp sensor issue, had a mpi engine that very hard to start ecm temp sensor thought is -40° F out, in West Los Angeles lol. Turned out the engine wasn't properly grounded, how it cranked and started at all is still a mystery.
Might replace it just to be sure, also I was thinking I have no idea how old this fuel is it might be a good idea to add some fresh.
Usually a distributor 180deg out will cause a bunch of back firing and having to fool with the distributor to get it to run so you could be right. I’ll echo what others are saying pull the #1 spark plug, bump it over until you’re sure you’re on TDC, verify timing marks at 0, then check distributor, then follow all your wires and ensure you have proper firing order. I’ll also add in have you tried starting it with the throttle slightly cracked? If it still doesn’t want to run do a compression check, if it passed that I’d check fuel pressure for good measure.
Edit- absolutely pull a fuel sample and look at it. You may be trying to fire rusty water!
Edit- absolutely pull a fuel sample and look at it. You may be trying to fire rusty water!
I’ve double and triple checked the timing and firing order, I think as far as the timing goes the chain either jumped a tooth or the dampener spun, that’s the only thing that makes sense to me at this point. Definitely will be looking at the fuel.
One thing you can do to maximize your timing is set it with a vacuum gauge. If you have a vacuum gauge you can connect it to a manifold vacuum source, and then adjust your timing until it reaches maximum vacuum. Then back in down one inch of vacuum, and then lock your timing down. It is not exactly the correct way of setting timing on a TBI, but if your timing is jacked for what ever reason this method will do for now.
is idling at 21 in hg, right now, I say the engine is tight. That also says the timing is not retarded, or the vacuum gauge is reading wrong. how does it rev ?
If you have physically checked the timing from #1 spark plug hole, then you already know whether the balancer has spun or not.
Revs fine, very responsive and smooth, just continues to come down too low and die, sometimes it brings itself back up but eventually it will come down low enough to die.
Oh right….I’m stupid. Yes the marks lined up at tdc so the balancer hasn’t spun.
Ok don’t kill me if this is the most obvious thing ever, but does this look like a normal spray pattern for tbi? 
I always thought it seemed a little weird but there was always a bit of a cone there so I thought it must be normal. But that steam coming out of the middle seems weird to me. I’m trying to attach a video of the injector firing but I’m not sure if it will work.
View attachment IMG_8753.mov
I always thought it seemed a little weird but there was always a bit of a cone there so I thought it must be normal. But that steam coming out of the middle seems weird to me. I’m trying to attach a video of the injector firing but I’m not sure if it will work.View attachment IMG_8753.mov
Is it the same on both injectors? Does it dribble at all after it's shut off? A leaky injector would be worse at idle than higher speeds, but might also show gas in the oil. What's the fuel pressure? I don't know if you can scan, but if it's pulling fuel at idle, that's a good sign of a leaky injector. If it's adding fuel, that's a good sign of a vacuum leak.
Yeah that injector is leaking. Stream in middle is bad, cone is good
