logray

I've upgraded my cylinders to 3.6L and want to run the 3.6L injectors, but I'm not sure if they will fit (oring/wiring) in my 1999 fuel rails.

The part number is 99660612200 for 3.6L and they are white.

Does anyone have any information whether this will work or not?

edit: Or if anyone can recommend an aftermarket solution. I'm searching but not having luck.

and edit: I see there is only one oring size, so I'm guessing they will fit... but not sure about wiring, can't see why it would be different though

Thanks

Charles Navarro

Yes, The 3.6 injectors will fit just fine, but really are not needed.

logray

Thank you!

I'm running the original gen 1 blue injectors. Even if they aren't needed, I am hoping my old injectors are just tired after 75k miles (even after the cleaning). The technician said after cleaning they were putting out 61 ml in 36 ms which equates to 131.76 cc/min (hope math is right) which is only 60% of the specified 220.7 cc/min for the orig blue 21 lb/hr injectors.

The newest 996 3.6L white 22.75 lb/hr injectors are supposed to put out 239.1 cc/min. (and interestingly they are also specified for 3.4L 2001 cars).

I ordered a set of the fresh 3.6L injectors hoping to resolve an issue with the DME fuel adaption indicating lean running after about 40-80 miles on a fresh DME reset.

FRA going slightly positive (+1.06 to +1.08) indicating lean running, perhaps the DME thinks based on the O2 readings it needs to dump more fuel because of the tired old injectors and larger displacement. After DME reset, with FRA at 0.98 and TRA at 0.00 or 0.02 the engine pulls very well and idles very smoothly. The power in mid/higher range RPM starts to degrade quickly as it goes towards lean indicator FRA with the DME adding more fuel.

And at idle, FRA starts to pull back fuel (-0.19 given enough miles), indicating rich, nearing a CEL condition at 25%. When it reaches the -0.10 area, the idle starts to get pretty rough.

I've triple checked wiring, new MAF, new O2 sensors, and blocked off just about every intake consumer including brake booster, SAI, and EVAP purge line and still the same results with the fuel trim. The intake is tight as a drum, and the engine is so smooth upon fresh DME reset, so these extra procedures with the intake are borderline crazy.

Charles Navarro

That's interesting but if the injectors are bad, that would certainly cause this. New (larger 3.6) injectors can't hurt, that's for sure.

logray

Yep, even if new injectors do not solve the problem with the fuel adaption, having ones that have closer to the right flow rate (and improved spray pattern) for the displacement I am now running certainly will not hurt the situation (and will probably help with performance at least).

I should know by the middle of next week what the results are.

Thanks again.

dcdrechsel

Not so sure it's that black and white .Substituting bigger injectors would depend on how the dme is programmed .If it is a table driven system ,new injectors will not exacxtly fit the predetermined tables with dme 5.xx .It may not matter but it is a question .

Paul 996

Logray,

You pretty much got the answer straight from the horse's mouth from Charles. I would run with that

logray

Jake says he uses the larger injectors in ALL of his 3.4L upgraded to 3.6L engines, doesn't re-use the old injectors since they aren't up to the task as much as the old ones.

And thank you Charles, don't mean to put you on the spot here. He did also qualify that yes they will work but there is a difference between "working" and "optimized".

Yes the engine works and runs, but just doesn't seem tuned as well as it could be.

The injectors are on their way to me and I'll have them in one way or the other. I'm not expecting it to clear up the fuel trim problem, unless the old injectors are bad and tired, but if it does fix it that will be a bonus.

I've also got a date with a smoke machine to triple check there's not any un-metered air causing the fuel trim symptoms (more likely culprit than injectors).

dcdrechsel

Guess it is black and white .

Cloudspin

[QUOTE=logray;9285469]Jake says he uses the larger injectors in ALL of his 3.4L upgraded to 3.6L engines, doesn't re-use the old injectors since they aren't up to the task as much as the old ones.

Jake used 3.8 injectors on the 3.6 to 3.8L rebuild he did on my '03 which would be consistent with what he told you. He also retained the factory tune. Hope the 3.6ers do the trick for you.

logray

Yeah thanks. I got some numbers from bypro which lead me to believe my injectors have just seen their better day... the car is getting the smoke machine treatment today.

Ubermensch

Something does seem off with your math if the numbers you listed originally are correct. Are you certain it's 61 mL in 36 ms? That would give a very strange value for cc/min.

-Shawn

logray

Right, I don't trust the numbers either. I emailed the technician but haven't heard back yet.

I redid the math because it was wrong the first time. Here it is right, but the numbers still don't make any sense whatsoever.

1 minute = 60,000 milliseconds

60,000 ms / 36 ms = 1666.66 36ms intervals per minute

1666.66 * 61 milliliters = 101666.66 ml = 101666.66 cc ??????

Even with the 3 ms numbers (typical idle injection time duration) it doesn't make any sense either.

38ml in 3ms was recorded.

60,000 ms / 3ms = 20000 3ms intervals in one minute

38ml * 20000 = 760000 ml(cc)/min

Ubermensch

Okay, at least we're getting the same numbers now. So you're doing the math right, but the starting values seem way off.

-Shawn

logray

Yep, it's sorta moot point anyhow, new injectors to arrive tomorrow or Tuesday! It will be interesting to see what the injector tech has to say if anything.

Also using the smoke machine I found two very very tiny intake leaks, one at the screw for the bracket below the throttle body, and another at the IACV. Both are patched up and it didn't seem to have much affect on TRA, after 70 miles of driving they are -0.06, so I'm sure with more driving it would continue to drop off. FRA is back to 1.08.

Also I took the car to sea level and read intake vacuum and it read somewhere around 17-18 in hg and steady. At 2000 feet where I'm taking most of the readings it's just a hair over 16 in HG. These numbers sound normal to me based on what I'm reading, but have asked the community for more data.