Cleaned Injectors and Changed Plugs and have issue

#1

Previously, the car dynoed at 141hp and showed that it was a little lean. So I sent the injectors to RC Injectors and had them all cleaned and put in new spark plugs (Bosch) that I’m told are gapped correctly. My brother did the work in Orlando, so I haven’t heard or seen the car, but right now its on the dyno, making 118hp and I’m told its really lean and feels like its down a cylinder. I can think of nothing that would make it run poorly. I pulled the whole fuel rail off, but that means taking off a fuel line, a vaccumn line, and two plugs off a coolant temp sensor, there really isn’t anything to get wrong. Any ideas?

#2

141/6 = 23.5
23.5*5 = 117.5

I would say they are correct. Figure out which cylinder has a spark plug or fuel injector that isn’t working. Make sure your plug wires are all tight (my favorite professional race team first step when the car comes in the pits not running right).

#3

Pull spark plug wires one at a time to see if the problem is global or just one cylinder. Each wire you pull should make the problem worse, until you find the problem cylinder. When you pull that plug wire, the problem won’t get worse.

Likely causes:

  1. The electrical rail isn’t fully seated down on one of the injectors.
  2. The round connector between injector harness and engine harness is crappy.
  3. A spark plug isn’t torqued in tight enough (22ftlbs IIRC).
  4. A plug wire isn’t all the way fastened at plug or dist cap.

If you find that the problem can’t be isolated to a specific cylinder, then you need to check fuel pressure, and check that the car’s voltage is ok (13.6v or better).

#4

They are gapped to .028 is that right?

#5

Touch your finger to each branch of the exhaust manifold. The one that doesn’t burn is where your problem is. :wink:

Or you could point one of them fancy laser thermometer thingies at the manifold.

#6

Is the A/F ratio lean across the entire rpm band? That would make me think of a fuel delivery or injector power/signal problem or a bad WOT switch in the TPS. If it is lean below 5K and ~14:1 above, I’d suspect the AFM or DME. More data, like the dyno plot with A/F ratio curve, whould help.

#7

I’d say that the fact the car is running lean via A/F report indicates that one (or maybe all) the cylindres is not getting fuel. Despite the fact that these injectors just came back allegedly all cleaned and blue printed, they could be bad. I had this experience with RC and it cost me hundreds of dollars changing TPS, fuel pump and fuel pressure regulator not to mention several dyno pulls.

Double check some of the items that the guys have suggested above and if all of that looks ok, put your old injectors back in. You might be surprised.

I have a set in my wreck in Largo if you need some others and I am going to Orlando on Thursday. I can drop mine off at your brother’s shop if you’d like.

Don

#8

Check the wires to each injector and spark plug are correct. Crossing the wires is easy to do and sometimes doesn’t always appear obvious. Usually it’ll run rough, but the injector are batch fired (correct?) so a couple cylinder may be firing out of order. Or is this not possible?

#9

Yes, .028 is right.

What did the report say about your injectors? How bad were they?

@ Steve, that manifold temp idea is genius. Every goddamned time I pull my plug wires on my car when it’s running, I get shocked. Rubber glove, cloth rag, rubber handled pliers, and by cylinder 4 it’s CRACK “Shit. You Bastard!” And then I turn the cocksucker off.

#10

[quote=“Ranger” post=57435]Yes, .028 is right.

What did the report say about your injectors? How bad were they?

@ Steve, that manifold temp idea is genius. Every goddamned time I pull my plug wires on my car when it’s running, I get shocked. Rubber glove, cloth rag, rubber handled pliers, and by cylinder 4 it’s CRACK “Shit. You Bastard!” And then I turn the cocksucker off.[/quote]
The next time you have a problem, take the car to Steve and see if he doesn’t scream on one or more of the header ports when he touches them.

If you are getting shocked when you pull a plug wire, the insulation on those wires is shot. Replace the wires with new OE parts.

#11

[quote=“jlevie” post=57439][quote=“Ranger” post=57435]Yes, .028 is right.

What did the report say about your injectors? How bad were they?

@ Steve, that manifold temp idea is genius. Every goddamned time I pull my plug wires on my car when it’s running, I get shocked. Rubber glove, cloth rag, rubber handled pliers, and by cylinder 4 it’s CRACK “Shit. You Bastard!” And then I turn the cocksucker off.[/quote]
The next time you have a problem, take the car to Steve and see if he doesn’t scream on one or more of the header ports when he touches them.

If you are getting shocked when you pull a plug wire, the insulation on those wires is shot. Replace the wires with new OE parts.[/quote]
My plug wires are OEM and less than a year old. I’d hate to replace the darn things, they are expensive.

#12

After you do the checking for the plug wires making the engine run worse, pull all the plugs to see if one or more is soaked in fuel. If one of them is, you know you have a spark problem. If none of them are, looks like you have a fuel problem.

You could even eliminate the shock therapy all together.

#13

The next time you have a problem, take the car to Steve and see if he doesn’t scream on one or more of the header ports when he touches them. [/quote]
OK, I admit it. I stole the idea (and wasn’t serious about touching the manifold). I was sitting on my arse watching the Rolex coverage (Lime Rock? The Glen? Can’t remember) and they mentioned that the Action Express car was having plug wire issues so the crew was checking the temp of each port. I’m sure they were using an infared thermometer, not fingers… :pinch:

#14

The next time you have a problem, take the car to Steve and see if he doesn’t scream on one or more of the header ports when he touches them. [/quote]
OK, I admit it. I stole the idea (and wasn’t serious about touching the manifold).[/quote]
Aw shucks. I was looking forward to watching while you checked each header on a misfiring engine.

#15

It wound up being one of my newly seviced RC fuel injectors that was just totally bad. Frustrating to send the injectors to them, pay, and then get them back worse than they were sent out. According to RC, when you service the injectors like them, its like Jesus himself personally measures the gas that is squirted in the cylinder each time. I got a spare injector from a friend, put it in and the car is running better. Couldn’t get back to the dyno, but at least the car is running now. Ranger, when I sent the injectors in, they had a low of 122 cc/min and a high of 135cc/min. When they came back they purportedly had a low of 139 and high of 141 cc/min with an “excellent” spray pattern.

#16

I’m no injector guru, but I don’t trust high mileage injectors anymore. I used to use take-off injectors that I had cleaned and flowed. But then I started having trouble with gas getting in my oil. It took a while but I finally figured out that 2 of my injectors were leaking. I know that’s a different problem, but the moral of the story is the same…high mileage injectors are iffy.

#17

Maybe it’s time to start using Marren instead of RCE. I chased my ass around that E30 while it was strapped to the dyno (dyno time costs the same, whether the car is running properly or not), second-guessing every part in the fuel and ignition system that I previously touched, only to find out that an injector that was freshly rebuilt by the almighty RCE was stuck closed despite the fact that the flow sheet reported that it flowed properly. “Oh, it couldn’t be the injectors, since they were just rebuilt by RCE.” Riiight. At least all of my work was right on the money. Next time this happens, I’ll check the RCE-rebuilt injectors FIRST (rather than last), as it will save me a ton of time and profanity.

I’d like to get this car back on the same dyno sometime, as I’m curious to see if it changed the 15:1 air/fuel ratio (which caused all of the alarm to have the injectors rebuilt) or if 15:1 is just as good as it gets with this 25 year old vane meter EFI setup.

Mark

#18

My plug wires are OEM and less than a year old. I’d hate to replace the darn things, they are expensive.[/quote]You need MegaSquirt.:stuck_out_tongue:

#19

http://www.cruzinperformance.com/fuelinj.html

#20

My plug wires are OEM and less than a year old. I’d hate to replace the darn things, they are expensive.[/quote]You need MegaSquirt.:P[/quote]

:lol: yeah, that’ll make all these problems go away :stuck_out_tongue: