lorenolson888

Hi Mr Ball,

let me interject my scientist's perspective...

If it were a sticky injector the plug should eventually show sign of running lean.... I think that is usually a white... overheated look... maybe someone else has a comment on what to look for ....

Could a bad brain do something like this... also have you reset the "brains" recently... I imagine so given the magnitude of the work you have done.... MAF + O2 can cause odd symptoms reseting may get around some of these...

I imagine you have the advantage of knowing a great number of people who can help you swap stuff around... so the cap, rotor coils is a good idea... Do you have your old plug wires... easy thinig to try is swapping an old one in.

The injector harness comment is probably a remote possibility... Putting SC on requires disturbing the wiring slightly...my wires are pretty crispy from all of the heat so maybe you have a bad lead... but the car runs differently with plug wire or inj plug disconnected... this suggests that the problem is slight like as in the stlcky problem mentioned.... A broken lead would probably effect across all conditions /speeds/loads...

Does the car run roughly only when you are only at idle and thoittle is in idle position... Does it run properly only when you are at WOT (bypass shut) or does it run well when you at partial throttle ...

Andy's manifold design has the SC bypass valve going right about to the #7 position... I think I remember that.... Could the connection be loose?

Can you swap your idle stab? It should be a lot easier to swap with Andy's setup as opposed to the stock setup...hehehe

Just throwing all air, fuel and spark related stuff out there...it sounds like it has to be one of those.. and it is affecting #7

So the same deductive technique was applied to other cylinders i imagine and that has led you to question #7 ...right?

Maybe try to run some of that techron stuff. maybe your ford 30lbs injectors had some manufacturing goo in it or some flashing that causes it to stick Actually the set of 8 sells for $220 so a extra for troubleshooting would be like $30... might be worth getting one and swapping it out....

Good luck Bill... Helping Steve with the racK this weekend? Wish me luck as I am going outside to finish up my car...

Loren

Bill Ball

Dave is number one on the sticky injector list. It is a real good possibility. When opening a fuel line fitting last week, the gas had some tiny black bits in it, perhaps some debris from when I modified a fuel line during the SC install (although why was it still sitting in the lines?). There are no old hoses that I know of (excvept perhaps back at the rear of the car) and only one injector appears affected, so it isn't a perfect explanation, but it may be that injector is not closing/oepning fully and it is more impactful at idle, as Dave suggests, whether due to debris or not. I like that idea. Good one Dave.

Adam C

IMHO the potential vacuum leaks on this system are insidious. I still get a surge every so often and I am figuring it out.

But Vacuum leaks I had were:
1. Around the large intake hoses. One of my elbows was dinged a hair (perhaps during shipping) and would not hold air.
2. The line that leads from the brake booster has very little purchase on the nipple coming out of the side of the intake horn = major leak.
3. Sealed ALL of the injector grommets with permatex - no leak detected but just in case.
4. Disconnected cruise control and HVAC vacuum lines just to isolate this system. Cruise control stayed permanently disconnected.
5. Intake horn to S/C needs a bead of sealant.
6. Make sure all the unused connections to the throttle body (3 of them) are disconnected.


Perhaps not relevant but I changed out my O2 sensor and it smoothed out the idle very nicely. I'm going to try MAF next, but frankly my injector harness looks a little scary as well.

Bill Ball

All the plugs had a clean slightly lean look to them. But they are very new. No tan light desposits (which would be normal) yet.

Those are evil thoughts, Loren.

The problem preceded a plug and plug wire change.

Dave had a good idea and several of you seem to agree.

This has been the number one suspect. It seems tight and a leak there has not been revealed by testing so far.
The stabilizer and throttle position switch were malfunctioning earlier due to a mistake I made in moving the ground for them during the SC install. My bad. All better now. There is no surging and the idle is almost perfect excepting the miss.

Steve is part way through on his own. May go over there this afternoon. Let me know how you are doing and if you could use help. Tomorrow afternoon is open too.

Bill Ball

Mine seem good.
I noticed that the nipple was short as well. Did you really document a leak there? How did you resolve that one?

I did #5. As to #6, there are 2 vacuum connections on the top and 2 on the bottom of the throttle body. Which are you using and which are blocked? I'm using 3 of 4, with the lower forward one capped. I understand that that is not how they are used on the 85 stock. The ports are slightly different as to where they are and how large the opening is in the inside the body. Anybody understand why there are 4 ports and how they should be used?

Tony

Having exorcised my car of a few demons, i would be leaning towards a tempermental injector or somehtng electrical in the ignition.. Id remove the injector and swap it with another one..or swap it with a new postion and see if the problem follows it around.

Any fuel cleaner you throw through there should loosen up any varnish and in doing so would "clean" them all. Especially doing the driving you have done over the last few hundred miles.
The odds of debris in the system contsantly finding the #7 injector aint gonna happen i dont think..

Airleak over a specific area wouldnt cause a "missing" type problem i dont think either. If it leaks its going to leak all the time at idle, not just now and then.

Search back a while when i had my injector probelms and you should find some handy schematics from the WSM that are colorized for easier viewing, if you cant find them i will email them to you. I bought a whole new set of Bosch injector leads on ebay dirt cheap. I may still have the sellers ID?

Yours is non intercooled so this may not be a factor but be sure you check the manifold for leaks, i had 2 bolt holes in places where there were no associated things to bolt through! It leaked air btewwn the gaskes i had made. I thought the gasket i made would take care of the problem but it didnt theres alot of suction and pressure involved especailly when its cycled from one to the other..leaks will crop up. .. Ive since fixed that and my manifold isnt leaking now. ?


Pull the rotor that fires number 7 and check the contact point?

Let us know what you find.

Dennis Wilson

Bill,

Don't want to scare you but a low rpm miss is also indicative of a compression leak (crossthreaded spark plug, leaking head gasket, burnt valve or cracked head). Have you performed a compression check?

Dennis

SharkSkin

Dennis, he checked that.

Bill, I think Brian D. actually pointed a finger at a faulty injector first. I simply pointed to a more specific failure mode that would explain your symptoms. Those valve caps sound real nice, but... well, it's your call.

Dave H.

i'll put in a vote for distributor cap.

spray water on the one with #7 while running and see if you get any arcing...

Dennis Wilson

Thanks Dave, I missed that. I still would recommend a leakdown test on both 7 & 8 as a static compression test may not pick up this type of problem.

Dennis

Bill Ball

Static compression was 225 lbs. I watched it for a minute and it did not change. Spark plug shows no evidence of cross-threading. I can do a leakdown later.

Bill Ball

I've got a couple of sets.

Dennis Wilson

Bill,

A regular compression tester has a one way valve that holds the highest pressure until the released manually. i.e. it won't show any leakdown.

Dennis

GoRideSno

Bill,
The test plan looks good.

If you found any sort of debris in your fuel system then you need to remove the injectors and have them professionally cleaned or there is a good chance you will damage the engine.

Andy

Bill Ball

The debris was in the cup I used to catch the gas when I broke the fuel fitting open. Not sure if it actually came from inside the line or not. Still, it bothers me, and you are right. I will remove the injectors and take care of them.