Mrmerlin

you will also need fresh heat sink paste if you swap the amps,
get a tube from amazon

SeanR

merchauser

what are symptoms of bad amps? how often to replace? normal maintenance, like spark plugs? cost?

mark kibort

i dont think its electrical due to the results of the tests we have been doing. sounds like it is miss fire, caused by lack of fuel in the #1 cylinder. and , it only happens at very low load ranges. (i.e. not at part or WO throttle). someone suggested a leaky valve might do this, but i did a compression test with a slow crank , it went up to 150psi, same as other cylinders on the first slow crank. (low battery crank) then, went up to 210psi on 3 hits on the compression stroke... same as other cylinders. im going to do a leak down, just to be sure. how does the non-sequential injection work. how is there atomization if the spray is into a closed valve flow path. maybe something the leaky intake vavle leans out the cylider on intake but not when under load.. just tossing out possibilities.

Mrmerlin

did you put any Techron into the fuel yet?.
Its a cheap way to fix your idle

mark kibort

yes, i got a bottle . i was going to drive it around today and see! i hope it works!

Mark

mark kibort

ok, drove about 30 miles today . no change yet.. : did some more tests.......... absolutely , the #1 cylinder when the injector removed, makes a repeatable miss, whereas all other disconnections is even as well, with a random miss. the question is , why??? and part throttle operation is NO issue at all. (low RPM to high RPM) the only time the miss is heard is extremely low power. (in neutral) pretty close to pulling the fuel line and swapping injectors to see if it follows the injector.

dr bob

mark kibort

that kind of noise, ive experienced before... thats a distinct noise IN the cam covers. this is definitely a miss, based on fuel . again, runs perfectly for the first 30 seconds , no miss, until it warms up. a little. the miss is very even when that #1 injector is pulled. and when any other injector is pulled, you get an even and also a random miss component. sure pointing to the low flow characteristics of the #1 injector or cylinder.
ill keep on driving it around to see if the miss goes away or changes. next might be to swap out the injector to see if the issue follows it. (and maybe look at the injector when it is removed to see if there is any obvious restrictions)

GregBBRD

Injector cleaning has become very popular....everyone assumes that a simple cleaning will fix everything wrong. Truthfully, it is a lot like "cleaning" a set of spark plugs....except spark plugs can be re-gaped and injectors can't be.

The problem is that injector cleaning doesn't do anything for wear.

It's not uncommon for us to have an injector start spraying poorly (creating a miss), a few miles after they are cleaned.

When Ford Motorsports was selling new injector sets that were a direct replacement for our injectors, life was much easier (and cheaper.) I very seldom even "messed" with having the stock injectors cleaned.....just installed brand new ones (with multiple holes and better atomization.)

Mrmerlin

I just put a set of 4 hole injectors on my 88 project the originals were trash.
Since Mark is on a very tight budget adding a bottle of Techron to the fuel system is the least expensive way to possibly fix a running issue.
Your right the cleaning wont restore anything on the mechanical clearance side,
but if its just dirt then the cleaner will work to remove deposits.

mark kibort

this sounds like it could the cause then. maybe the lower fuel line pressure, along with the use of less cheveron and more Union 76 over the years ,caused this one injector to slightly malfunction. again, the car runs perfectly at any thing OTHER than very light throttle. and this issue seems to point to one injector, (#1). dont know if its worth worrying about ,if it doesnt effect WOT performance. plugs all look great , even after the 2 race weekends....so, its off to the runoffs!

mark kibort

its not changing at all. ive always though the snake oil liquids are BS. sure, fine for long term cleaning and avoiding issues, but not for a "repair". the only liquid ive ever used that worked was barr's stop leak!
so, im narrowing this every day down to the #1 injector. why dont i just buy 1 30# injector and replace it. anyone know what you guys had me buy? i cant find the record of it. i might have bought the set of 8 from the list for the stroker build. i think i remember them being ford injectors with the 928 seals on them. very temped to just put on a set o 24#ers and kick up the fuel presurre to 65psi and go to he dyno.... OR, just replace the one injector with anything and see if it fixes the issue, OR swap it to the #3 cylinder......that way if it follows it, we know its ok for WOT use and i can swap it out later. thoughts. it just sounds crappy idling and higher RPM idling in neutral.

mark kibort

another key observation is that the miss is completely gone at start up, showing even further, that it is fuel related. as soon as temps rise slightly , the miss begins. im going to look at the part numbers on the injectors and just replace the one that is suspect. good idea?

FredR

During warm up your injectors are open longer so more fuel gets through. When warm you notice the problem at idle but the chances are the same problem translates through the rev range but you just do not notice it.

As I intimated many posts ago, u/s cleaning can and does improve things but obviously it will not cure mechanical wear. If you know the age of the injector/mileage covered and it is moderate to low then cleaning is your potential answer. Either way unless they are flow checked/cleaned you are going no where with the problem unless you get a new set of injectors

One of these days you might just turn on the lights and Sharktune the poor thing! Dicking around with fuel pressure is what it is- dicking around!