dakinez

I've tried a few different plugs. I think the plug is fouling because the miss does follow the plug, but after a few minutes of running the miss reverts to cylinder 5. I've tried new plugs and old plugs, same behavior. I've tried different plug wires too (I put all new ones on, I tried several of the old ones and switching the new ones around), same result. Also tried putting the old dizzy cap back on, same thing. My fear is that if it isn't fuel, and isn't ignition, it must be valves or rings - which would make me cry. My last compression test had all cylinders around 150, give or take a couple of lbs.

I ran the AFM voltage test, it was all dead on. Turns out I have another AFM that came in a box of parts I picked up; I tested that too and it was almost the same (range on the original was 2.58v to 11.56v when the battery was 12.52v; on the spare AFM it was 3.00v to 12.15v). Both were smooth sweeps. I also disconnected ALL the vacuum lines except the throttle body to distributor. I capped everything, and it made no difference whatsoever. I even took off the crank case hose that feeds the PCV valve and capped the PCV (but let the crank case hose breathe), still low vacuum. Based on my elevation I should be getting 17.5, I'm actually getting 15.5. When I pulled off the PCV cap it was full of fuel, I guess it is the lowest point so I'm not too concerned but I did change out the cold start injector (I had a spare from another manifold), no changes there either. I do have a misfire, and its the strangest thing. At idle if I pull off each injector plug one by one, all cause the misfire to worsen (so I don't think its a complete misfire, just partial). If I pull off the spark plug caps one by one, each causes the misfire to worsen except cylinder 5 - no change to the engine speed/smoothness when I pull that one. That does not tally with pulling the injector plug. Whats even stranger though, is if I hold the plug cap near the end of the plug so it arcs, the misfire goes away. How can that be? If I put the cap back on the plug, the misfire returns. It's very repeatable. The vacuum also comes up when it is arcing and the misfire clears. I've tried different plugs and different wires, same thing with any combination. The plugs are coming out very black and oily.Here is a video demonstrating

This is good stuff, thanks guys. I'll do the voltage test on the AFM tonight. I have an analog meter but it's pretty crappy and didn't do a good job in this case. I may invest in a better one just for resistance testing. You are right, post #13 has the front firing, popping through the intake. My plan tonight is to do the voltage test on the AFM and post the results of that, then take a vacuum reading and try disconnecting vacuum lines etc to see if I can increase vacuum anywhere. Thanks!

I dunno man, looks like you drink too much coke to me So over a period of time, injector #1 shot nearly double injector #3?

I spent another hour on this tonight, here's what's new. The ticking is absolutely definitely from the injectors. I proved this using the highly scientific screwdriver method (sharp end on the component, plastic end on my ear). The valve cover just has some soothing swirly gurgling sounds, on the injectors I can very clearly hear the individual firing of each one (addictive actually :). Of course just because they're firing doesn't mean they have a good spray pattern etc, but that particular mystery is solved. It sounds more severe in the video than it does in person. On that basis, I'm going to save the valve adjustment for another day. Agree? I had a really good look under the intake, all around the both manifolds, all around the connection for the EGR etc, it's actually really clean and appears to be in really good order. I don't see any evidence of any leaks around it. I *think* it's good, but I will try and find some kind of smoke generator; I'm not a big fan of spraying starter fluid down on the exhaust manifold. I checked the timing (properly this time - removed and plugged the distributor vacuum). It sits right at 10 degrees BTC when steady, moves as far as 20 degrees under acceleration, then drops back to 10 under deceleration. Am I right in thinking that is just where it needs to be? Hard to see in the video, but its there. Check this out though. I pulled the AFM boot off to check it, you know how it goes, keep pulling things off :/ Well i decided to check the resistance of the AFM through it's stroke. Have a look at this video. It jumps substantially. Would you agree that it shouldn't do that? It ranges from 38 ohms resting, and peaks at around 572 ohms about 3/4 through, but jumps all over the place. Could that be sending whacky signals to the ECU?

I made a copy of your card, great idea!

Hah, that answers my other question! I hate valve adjustments

This is great stuff, thanks for the direction. The PCV hose was replace by the PO. It's actually two hoses, one inserted in to the other. When i got the car it has some kind of goo *sort of* sealing them together. I cleaned all that up and used a bonding cement. I'm confident that one is good, but I will go through all the vacuum lines, the throttle body boot, etc again, and get down under the intake too. Do you agree that even if the valves could use adjustment, it wouldn't be the cause of this poor running?

Yes 10 degrees at idle but I realize that I did not remove & plug the dist vacuum line :/ I was hoping the ticking was just the injectors (and normal), I've not been able to track it down between injectors and valve cover. It could be valves. i guess I should check them too.

You mean ignition timing right? I'll do it again tonight, but it was right at 10 degrees. Here is a video from last week.

Thanks for this, I'll check it. I did go through all the EGR equipment as much of it had been removed by the PO and the car barely ran at all back then. But I don't remember checking that, so I'll make sure. I did notice I have tiny exhaust leak from cyl #6 where the manifold bolts up to the head, the last bolt is missing; so i need to fix that but I don't feel like it's the cause of this current condition.

Gas is somewhat fresh 89 octane. I ran a lot of seafoam through, when that was done its on to just clean gas, didn't seem to make any difference. I'm really struggling with what to look for next. I'm going to post up a vacuum vid,

I got this done today. I used a basic 1k potentiometer and spliced it in per the AtlanticZ article. Things are definitely better, I run it at full resistance, and the backfiring through the intake has mostly gone away. I was expecting to fine tune it, but it basically just needs to be at max....... The problem I'm having now though is smoke. And its pretty dark, so I'm fairly sure it's running very rich now. Is it likely that I have simply masked an underlying issue, or should I persevere with fine tuning the potentiometer? Any other tests I can do on components & circuits beyond what is in the EFI bible? Thanks!

Of all the hours I've spent looking at AtlanticZ articles I've never seen that one, I can't understand why! Thanks for this, I'll give it a go over the next couple of days and see how it looks!

I think I've tried everything I have read about. Here is the problem: Car runs like silk when cold, like crap when hot. It backfires through the intake, stumbles a lot, will only build rpm with a lot of feathering, but when it's high in the rpms there is power there (I can burnout). I'm looking for suggestions on what to try next. Here is what I have done/tried: New plugs New plug wires New dizzy cap & rotor Set timing to 14 deg New Fuel pump & Fram filter (between tank & pump) New main filter Tested fuel pressure, it's a little low at approx 33psi at idle, but goes as low as 24psi and as high as 36 as rpm fluctuates Cleared fuel lines Replaced throttle position sensor & connector (confirmed good) Replaced water temp sensor plug Replaced thermotime switch plug Replaced cold start connector Replaced Air regulator connector Cleaned all injector connectors I have seafoam in the fuel (interested to hear if this could be an issue?) I did a seafoam smoke bomb clean I have also gone through the EFI bible and done all the circuit tests, everything is within range. The fact it only seems to be a problem when hot suggests to be its a fuel related issue, rather than ignition or vacuum leaks etc (I can't find any vacuum leaks) I'm all about testing things rather than randomly replacing things - as a first choice anyway. Any help much appreciated!