injector cleaning and calibration

[ShadowBolt]

I know at least one of us that has had this done. Is there really any reason? If one or more injectors was not working correctly I would assume you would know you have an issue and the OBD2 system would alert you? It is only about $150.00 to have a set done but I don't really know if it's needed?




JJ

[Pranav]

I've done it a number of times in the past, worth it if you have some doubts and never had your injectors cleaned before. Not only can a dirty injector be low on flow, but it can also leak fuel when closed. I've had cases of both in the past when I had recurring fuel line contamination issues until I replumbed.

Typically on OBD2 cars you typically only get a warning if you lost connection to an injector, or if the computer is having to add positive fuel trim over a certain threshold. For LT1s I believe that number was 25% more fuel than normal before it throws a CEL, which is a lot. Have only seen that once when a vacuum port was left disconnected. Not yet sure what the % cutoff is on LS1s but hope to never find out.

One quick way to check is run the car, let it warmup, then compare the short/long term fuel trims between bank 1 and bank 2. My 5.3 with cleaned injectors idles with 4-7ish percent positive fuel trim and is never more than 3% off bank to bank, My 125k mile Tundra is a few % less, etc

Think of it this way, if you have 4 injectors on a bank with only 3 of them are pushing out 100% of the fuel they're expected to spray, and the 4th one is clogged and only puts out 50%, perfect/ideal math would say the computer would richen up the bank 12% to make that bank run 14.7 AFR again at idle, so you'd still have a "safe" +12% TRIM over normal, which usually wouldn't trip a CEL and you wouldn't know unless you watched fuel trims or felt the car was running "rough"

To take another example, during R4 at MSRH I had an injector connector work loose because it wasn't clipped in. It was running rough, had an injector harness code, and the + fuel trim on that bank was "only" 15-17% from from I recall, which would've never tripped a lean code. That's an extreme example with complete loss of one injector though.

[ShadowBolt]

I'm sure all of this is true and correct I just wonder how real an issue this is? How many have had to have then ch=ecked?

JJ

[39PitCrew]

I know at least one of us that has had this done. Is there really any reason? If one or more injectors was not working correctly I would assume you would know you have an issue and the OBD2 system would alert you? It is only about $150.00 to have a set done but I don't really know if it's needed?




JJ

I'm sure Sean would happily tell you about the injector that failed open
and grenaded a new engine. Although doing an injector clean and test
might not have found the offender prior to its failure.

[ShadowBolt]

I'm sure Sean would happily tell you about the injector that failed open
and grenaded a new engine. Although doing an injector clean and test
might not have found the offender prior to its failure.

I agree I doubt this service would have prevented Sean's issue.

JJ

[Pranav]

My three times I've had them tested/cleaned

1. First ever start of my first LT1 when building the car, would only run on starting fluid because most of the injectors were completely plugged with varnish

2. Blew a motor and wanted to check, glad I did because they were starting to clog again with varnish and one was leaking slightly when closed; this prompted me to re-plumb, but was not why I blew the motor

3. New LS swap, immediately sent used ls injectors from ebay off for cleaning; didn't do initial test because the tech smelled bad fuel when taking them off the rail, so they went straight to cleaning. No clue if they were clogged or not but they definitely sat for a while and didn't feel like repeating #1 again nor cheaping out and putting a new motor at risk.

Ultimately if you suspect you have a fueling issue then it would be worthwhile to spend the $150 to find out rather than risk another motor swap. If everything is fine, you're not running lean at WOT, fuel trims are not way off, then maybe not...

As far as what causes injectors to clog and leak, in my case it was definitely varnish from old fuel line and definitely fixed by cleaning, but at the time it was a very small leak. There's no telling what caused Sean's injector to stick open, was it more and more varnish build up or did it break? Sean if you have that injector you should donate it to Injector RX here in town so we can find out lol.

Even despite all of this, we haven't taken into account if a perfectly clean injector works fine when cold but has trouble firing when hot; a lab test wouldn't figure that one out I think...

[dtanker65]

New injectors, cheap insurance.....

[BryanL]

Jerry did you clean the MAF? Check the cylinders with your scope? You obviously have something going on with either the fuel or electrical/spark or both. Still running weird?

[marshall_mosty]

I typically have the injectors cleaned every 4-5 seasons as cheap insurance. It's good peace of mind to get a flow sheet showing they are all within a few percent of each other since the computer can't tell exactly what is going on with each cylinder independently..

At least you guys can check each bank thru the ECU. Even with my "fancy" EFI, I only get to monitor one bank... Now, I've selected the bank that has historically been on the lean side, so hopefully that will equate to a longer life span for the engine.. :)

I used a place in San Antonio last time (Mike Montgomery's recommendation) for cleaning.. I can dig up that info if you need it.

[Supercharged111]

I've had 2 sets cleaned, both entered within a few percent and left within 1-2cc/min of each other. Stock LT1 injectors generally get turned away. Apparently the colied wire that forms the electromagnet to open the pintle has insulation that gets washed away not only by fuel over time, but also more aggressively by the compounds they use to clean the injectors. One of the reasons stock LT1 injectors blow. There are certain LS injectors that play nice, but you really need to do your homework.

[ShadowBolt]

For some reason the 55 got leaner throughout the weekend. Started at 12.3-12.5 Fri. on the dyno to 13.5-13.8 in the last race on Sun. It also is not running very good at lower RPM's. WOT is fine but still about 10-12 hp down on power from every other engine I have had. I tried to use the old block and just honed the bores and put in new Pistons, rings, and rod inserts. I'm pulling it out this weekend. Have a new (not rebuilt) bullet on the way. I will clean the MAF or replace it. And I just wondered if doing the injectors is worth doing. Still not convinced. Something is wrong and if I can't figure it out prior to Cresson I will have to skip it.

[Supercharged111]

I wouldn't be leaning toward injectors personally. Was the weather different between those 2 events? In open loop, my cars all suck at DA correction. They rely heavily on the 2D map that affects open loop fueling which I believe is load vs coolant temp applied to all RPMs. This is how I've seen the OEs do it, but it's possible Ford did it different on the 4.6. I wouldn't count on it though. That's why mods like cams and headers sometimes really throw the car for a loop (mostly when they affect the VE curve, if it's a global bump the ECU can generally compensate). That's why a fuel pressure change only affects WOT AFRs for a short period of time if you're closed loop. The car applies what it learns in closed loop to open loop. Are you sure something didn't happen that the O2s are picking up on like a vacuum or exhaust leak? Did you monitor both banks for AFR or just 1?

[Pranav]

What are your short term and long term fuel trims? Your OBD reader will tell you that.

[ShadowBolt]

All this crap makes my head hurt. I installed new O2's and no change. The wideband is on the right bank but after the X pipe. I have not looked at fuel trims. I was getting P1130, P1131, P1150 and P1151.

Jerry

[dtanker65]

Looks like the same fault throws all of those codes. My buddy says with the BMW it is very common to have vacuum leaks and the dealerships use a smoke generator to find them. Cigar smoke through a piece of hose works too. Good luck Jerry, I'd look for something mechanical after the re-assembly if it was good electronically before, just my two cents

[Fbody383]

Cigar smoke through a piece of hose works too. Next race features a cigar and brandy corral with vacuum leak detection

[BryanL]

There is something going on with the 55 and I'm like Jerry that I don't know about fuel trims and what not. But I don't think it's the engine as it's something fuel/ignition/electrical I think. Why are you pulling this engine now Jerry? Did you clean the maf or inspect it. Did the camera work? I hate to see you pull it to find it was a vacuum leak or a loose connection.

[Pranav]

Look at the fuel trims, and while you're at it look at all of the other sensors to make sure they are reading right.

If a bank reads +10% at idle that means it's having add 10% more than usual which would indicate vacuum leak, bad/low injector, fuel pressure, mass airflow or manifold pressure as possible culprits.

Doesn't your 4.6 have a variable computer controlled pressure regulator?

You can read all this off your phone and a Bluetooth obd adapter which I think you guys have. Bummer you're not in Houston as we have 17+ dynojet and they'd do a good job of helping figure out what's going on at WOT/high rpm if you can't figure it out in idle or driving around the block.

No sense trying to poke at it without reading the wealth of data your computer tracks and makes available via obd2, just IMO.

[ShadowBolt]

Look at the fuel trims, and while you're at it look at all of the other sensors to make sure they are reading right.

If a bank reads +10% at idle that means it's having add 10% more than usual which would indicate vacuum leak, bad/low injector, fuel pressure, mass airflow or manifold pressure as possible culprits.

Doesn't your 4.6 have a variable computer controlled pressure regulator?

You can read all this off your phone and a Bluetooth obd adapter which I think you guys have. Bummer you're not in Houston as we have 17+ dynojet and they'd do a good job of helping figure out what's going on at WOT/high rpm if you can't figure it out in idle or driving around the block.

No sense trying to poke at it without reading the wealth of data your computer tracks and makes available via obd2, just IMO.

Do not talk to me while you are in the mountains skiing. I can't hear you......la la la la la la la la la la la la

[Rob Liebbe]

All this crap makes my head hurt. I installed new O2's and no change. The wideband is on the right bank but after the X pipe. I have not looked at fuel trims. I was getting P1130, P1131, P1150 and P1151.

Jerry

I'm no engine guru, but does having the wideband after the X-pipe throw any flags to anyone else? I'm thinking it is too far away from the engine giving the exhaust time to cool a bit and affect readings. I'm also curious about the crossing of the exhaust streams causing erratic or erroneous readings.

I could be way off base, but every factory O2 sensor I've ever seen is relatively close to the exhaust port. Kinda like taking pollution readings either near or far away from the source.

[dtanker65]

Do not talk to me while you are in the mountains skiing. I can't hear you......la la la la la la la la la la la la
Only Pranav.... Shooshing through the picturesque winter wonderland thinking about CMC fuel ratios. What is wrong with us?.....

[Pranav]

I've had 2 sets cleaned, both entered within a few percent and left within 1-2cc/min of each other. Stock LT1 injectors generally get turned away. Apparently the colied wire that forms the electromagnet to open the pintle has insulation that gets washed away not only by fuel over time, but also more aggressively by the compounds they use to clean the injectors. One of the reasons stock LT1 injectors blow. There are certain LS injectors that play nice, but you really need to do your homework.

Yeah my injector shop told me to get rid of mine the 2nd time around.


Do not talk to me while you are in the mountains skiing. I can't hear you......la la la la la la la la la la la la

LOL.

[Pranav]

Only Pranav.... Shooshing through the picturesque winter wonderland thinking about CMC fuel ratios. What is wrong with us?.....

They call us gearheads for a reason. Some of these chairlifts are long, lots of time to think.

[Suck fumes]

yah having the sensor back that far will throw off the reading a little. I have always installed them just after the header connection and before the X pipe. It says in the instructions for those gauges too to mount it as far forward as possible.

[ShadowBolt]

yah having the sensor back that far will throw off the reading a little. I have always installed them just after the header connection and before the X pipe. It says in the instructions for those gauges too to mount it as far forward as possible.

I'm sure you are correct about the sensor needing to be in the front O2 bung but if so how does the computer get info on each bank if it only has one O2 connected to the computer? The rears are after the X. I guess I need to re-read the instructions.

JJ

[Suck fumes]

use weld in bung that comes with the gauge and weld it in after front 02 but before X pipe

[rleng1]

Next race features a cigar and brandy corral with vacuum leak detection

IN the Rockies, I just have the dudes next door bring over their bong.

[Supercharged111]

IN the Rockies, I just have the dudes next door bring over their bong.

Don't act so innocent, it's not like you have to piss in a cup anymore.

[Pranav]

Was the car running hot at all when the AFR got worse? If not it may just be a garage accuracy issue.

[ShadowBolt]

No it did not run hot. Also I posted this but my post has not shown up. All my O2's are prior to the X. I run the stock units in the front two and elimanators on the rear with the wideband in one of the rears.
I just got the engine out and this all may be PVC related. Oil burned on every piston and I was filling up the catch can every two races. Normally we don't get two ounces out after a whole race weekend.
JJ

[Pranav]

I know you were saying you kinda slapped that motor together and had some rough spots in the cylinder walls, maybe you just had low compression and poor piston seal? Would explain why you were down on power and had so much blowby that the PCV can filled up?

To my point earlier on the wideband maybe it needs to be calibrated or enough PCV oil got through exhaust and fouled it up?

Pull all them sensors and see if they're fouled up?

Was thinking about your problem on the ski lifts today.

I also came up with an idea to use a high speed bilge fan to make an air cushion windshield wiper/blower now that I'm running out of stuff to fix on the car.

[BryanL]

Jerry hurt a motor at Hallett with I think broken ringlands and detonation. Seems like the same thing has happened to the motor put together this winter. It seems something fuel/ignition/electrical related. Sure the a/f could be a little off due to the gauges location but it should still read the same reading throughout the weekend and not get leaner.

[ShadowBolt]

No detonation damage this time but tons of oil being burned. New pistons covered in burned oil. Maybe the oil was screwing with the wideband? I just read about an issue with the Trickflow valve covers. I only got them because I broke one of the originals a year or so ago.


JJ