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928 GT, accelerates fine, misses when cruising

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Old 11-05-2018, 03:25 PM
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worf928
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Originally Posted by macerl
Specialized ECU Repair, Oakland Park, FL; https://www.ecudoctors.com/; referred by my previous mechanic in Tampa area, Leo Leal, German Specialties.
That’s what I was afraid of. Yours isn’t the first, second, or third LH 2.3 they’ve messed up.

https://rennlist.com/forums/928-foru...placement.html (read past the yelling.)

They do not, I think, understand the common failure mode that is, seemingly, unique to the LH 2.3 which isn't exactly a ‘high-volume’ unit even when compared to other Porsches.

Your symptoms are consistent with the LH providing early warning signs of its demise.

http://www.electronikrepair.com and https://jdsporsche.com

are the go-to resources for LH 2.3 rebuilds.



Old 11-05-2018, 04:48 PM
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best thing to do is swap your computer to a well running machine and see if the issues follow the computer.
Add a bottle of Techron to the gas and do short rides so it has time to work
Old 11-07-2018, 11:05 AM
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Techron fuel injector cleaner or fuel system cleaner ? I presume fuel injector cleaner...
I will talk with my mechanic about test swap of computer with one of his other customers.

It may be time to send LH and MAF off again.
I understand Ott's Performance Engineering in Oregon is an authorized agent of JDS in UK.
Should I send the EZK to them also?
Old 11-09-2018, 04:12 PM
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What is the relative cost of cleaning and re-balancing injectors vice replacing 28 year old injectors with new ones?
A set of new injectors appears to be in the $200-$250 range.
Old 11-09-2018, 06:10 PM
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Originally Posted by macerl
A set of new injectors appears to be in the $200-$250 range.
Where?
Old 11-09-2018, 06:59 PM
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Kevin in Atlanta
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I use Injection Connection here in GA - they charge $180 to rebuild and balance them.
Old 11-09-2018, 07:38 PM
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my bad. Off brand and remanufactured.
Old 11-09-2018, 11:12 PM
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Call Roger and order a set of 4 hole injectors they are plug and play
Old 11-09-2018, 11:59 PM
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Injection Connection (this one is in PA)
or Injector Connection (this one is in GA)
Old 11-10-2018, 06:43 AM
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Kevin in Atlanta
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Injection Connection in GA

I've also bought 4 hole injectors complete with the correct notch for our rails for a bit more.

If you do decide to use them, I'd provide the bottom o-ring from Roger along with the injectors to be rebuilt.

Great folks.
Old 01-08-2019, 05:30 PM
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Received MAF and ECUs back from Louis Ott, MAF and EZK fine;
his analysis of LH also showed some missing.
- purchased rebuilt JDSPorsche LH.
Reinstalled all and test drove; let idle in driveway for 5-10 minutes.
Then drove neighborhood speeds to refill with gas (5-10 minutes).
Then took onto freeway. Did not push hard, just normal entrance onto the highway.
- ran perfect for ~30 miles, then again started missing at cruise speeds when not accelerating.
- still performs fine when accelerating onto freeway and when passing.
- only issue when moving along with traffic at cruise speed.

My next thought is oxygen sensor.
Old 01-08-2019, 05:35 PM
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Injectors. I've not seen any evidence from you that they have been replaced with new, or cleaned and rebalanced.
Old 01-08-2019, 06:00 PM
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I have not done anything with injectors. I was hoping it was something cheaper and easier.
Ok; injectors next.
Any good posted pictures and instructions for injector removal and replacement?
Old 01-08-2019, 06:40 PM
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most important thing is to use compressed air to blow the sand away from the injector bores before you remove them,
then spray some PB blaster on the lower seals prior to removal to let them separate.
Old 01-08-2019, 07:04 PM
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Originally Posted by macerl
I have not done anything with injectors. I was hoping it was something cheaper and easier.
Ok; injectors next.
I think a new Bosch 02 sensor is slightly more expensive that sending your injectors to Witchhunter. According to your posts, your 02 sensor is only a couple of years old whereas your injectors are original.
Any good posted pictures and instructions for injector removal and replacement?
Injector R&R is one of the first things that happens in an intake refresh. So, any good Intake R&R procedure will work. Mine's available on the 928 International website. http://www.928intl.com/repair/intake1b.pdf

Dwayne's is available via his 'garage' site. Search is your friend.

Adding to what Stan wrote above, upon reassembly:
- lube (new) injector o-rings with a rubber-friendly lube
- injectors go into the fuel rails
- injectors are clipped to the fuel rails
- rails are installed and connections tightened
- fuel pump relay is bypassed to run the pump and check for leaks

Follow this order. Do not deviate from it or decide to re-arrange the order. Do not skip steps.


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