87z16

hello all,

i have a 1985 monte SS with an LT1 from a 96 roadmaster with OBD1 conversion, 52 mm tb, airfoil, free flow duals and a new 4L60e with an 8.5" 3.42 posi from a GN and the computer has been recalibrated to a 96 Z, as well as suspension mods, but that aint important to this.

i have a problem that appears that 3 injectors are not firing.

i disconnected each injector and watched/listened and i saw that 3 of them didnt make a diff if they were on.

i checked all of them with a noid, they all are getting spark.

i checked the ohms of the injectors and they all vary between 13-13.3ohms

so i figured that maybe the injectors are clogged. the engine has a roughness but no codes come up. i checked that with a snap on.

ive done a search into this forum about injectors and i understand that since its basically stock that i should keep the 24# injectors, but i should go get SVO.

ok, but i didnt get a ford/bosch part# would anyone have that # for me??

and please let me know if i missed a step.

thanks for your help!!
tom

here is my site:

http://www.1987aerocoupe.homestead.com

joeSS97

I would look for some used ones.A lot of people have them that went bigger...If you get SVOs,you will need reprogramming,as they are rated different...Mattter of facy,I have a used set.

slopokrodrigez

Your missing something big time. First off, you're not throwing a code for missfires? I find that very odd. You say that 3 aren't firing but yet you say they are getting spark LOL well we know what you mean. What makes you think there is a problem of any kind? In other words, what are the symptoms?

Have you swapped injectors to see if the problem moves with them or stays put?

Do you suspect injectors due to cold cylinders? If so there are other causes for dead holes. But there is still the issue of not getting a misfire code.

Let us know.

Dave

87z16

thanks for the quick replies.

im sorry, i am relatively new to the EFI thing and i dont know all the proper terminology. thanks for the patience tho!!

well the car runs on the rough side and in midrange kinda stumbles b4 it takes off.

the passenger of the block has, it seems, higher compression, but it still has the cat.(could be a collapsed flowie??) the drivers side is free flow due to my stupidity .

then when i removed the connectors 3 of them didnt make a difference but the other 5 the engine stumbled.

i dont think it has anything to do with it but i believe the tensioner is squaeling.

OH, and when i took it to be inspected it failed. the guy said it is running lean and all the cylinders are probably not firing. so i thought it was the opti or injectors.

by the way it is a 60k mi motor.

and i dont know how to check for cold cylinders and i didnt swap injectors.

thanks again!!

slopokrodrigez

Removing the injector harness from an injector and getting no substantial change in idle quality does not mean the injector is the problem. It only shows that "maybe" the cylinder wasn't firing. There are several reasons the cylinder may not be firing. Fuel is one of the reasons but you "checked" for a signal with a noid light, so that should rule out the injector. But swapping it would double confirm that. You may also have a fuel delivery problem. Checking the fuel pressure while the car is behaving pourly will help in further finding the problem.

The other causes for not firing would be loss of spark and last, loss of compression.

If I read what your saying as you have a cat on one side of a dual exhaust setup but not the other. The absolute first thing to do is equalize the back pressure situation. Obviously the best thing to do is relieve the side with more back pressure but then I don't know what your smog situation is in your state.

There are several ways to check for a cold cylinder, you already did one test by removing the injector clips and noticed no worsening of the idle when you removed 3 of them. Other ways are: remove the spark plug wire while it's running, use a water spray bottle and squirt the exhaust manifold and my favorite, use an infrared thermometer to measure the manifold temperature. If you confirm a dead cylinder, you have to determine why. Removing the injector clip causing the idle to not change does not mean the injector is the problem. You could have low compression or no spark. Got it???? Now if you truly do have dead cylinders, you have to find out why.

Pull the plugs and look for spark when someone cranks it over. Look at the wires for bad contacts, split or burned insulation and measure the resistance of the wires WHILE you flex the crap out of the wire. Look at the condition of the plugs to see if any are fouled indicating running rich. Look for indications of running lean. If all that looks ok, it's time to do a leak down test.

You may actually have a bad injector that's why swapping it/them can help find the cause. It may very well be the problem if you have a dead hole or 3 and someone said you were running lean.

I've seen fuel rails get a lot deposits in them from a vehicle that sits for long periods of time.

Injuneer

Apparently you missed this part of his initial post:
There is no misfire detection in OBD-I.

His post is confusing, because he says "the computer has been recalibrated to a 96 Z,".... which is not consistant with an OBD-I conversion, unless he just means he's using the program tables.

87z16

hello,

sorry about the confusion.

this car was purchased with the drivetrain already in it the engine/tranny was originally from a 94 9c1 along with the computer. the previous owner updated the engine to LT4 specs but took out the rockers due to the noise and had the ECM reprogrammed using 96 z28 specs. a crank bearing slipped and i replaced the engine with a stock engine out of a 96 roadmaster 60k mi, using the original set up from the 9c1(computer, wiring, TB, lt4 knock sensors). i also added a new 4L60E.

the car baisically drives ok with nice power but it has that stumble, roughness and poor fuel economy. before the swap i used to get better than 20mpg and now it seems significantly less but it is not registered and i cant take it for a long drive to see.

i guess i should have started from the beginning before, sorry!!

87z16

any other suggestions???

THANKS EVERYONE!

slopokrodrigez - i will check those suggestions from u. they r really helpful!!

joeSS97 - just in case how much r u asking for the set??