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Unread 01-17-2012, 11:37 PM   #1
xj2k1
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Precision Auto Injectors?

Has anyone out here, tried the Bosch upgrade injectors for the '99-'04 4.0 from Precision Auto Injectors? I'm ready to pull the trigger on a set. But, for 150 bucks, I'd like to know a little about these guys. Any feedback, positive or negative is appreciated.
Thanks

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Unread 01-17-2012, 11:48 PM   #2
silversleeper
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I've received a set of injectors from the guy. The product was shipped fast, clean and ready to install. There are a ton of other contributing factors to my crappy gas mileage that I can't really comment on whether or not these injectors improved mine in particular. But they definitely bought me some piece of mind.

For the little extra you pay, I'd say its worth it over buying a questionable used set. New filters, optimized spray pattern, flow matched, you really can't go wrong with them.
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Unread 01-17-2012, 11:58 PM   #3
keepishop
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I got a set of renix ones. 2 were bad. Was pretty pissed off that they didn't answer my emails. After talking to them on the phone they made it right though. I guess they are just car people and not computer people. They sent me new injectors and a label to send the old ones back.

Anyway, they messed up on mine, but did a good job making it right quickly.

Oh, HELLA fast shipping. Gotta love buying American.
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Unread 01-18-2012, 12:41 AM   #4
motoxxxman
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you absolute best bet is to simply have the stock injectors cleaned/"rebuilt" by the best:
www.witchhunterperformance.com
$20 per injector for testing, analyzing quality, leak testing, multiple cleanings, re-testing, new o-rings/filters/baskets/pintle-caps. 2-3 day turnaround.

I've been using these guys for years, and every single time it's incredibly quick turnaround time and only top notch work done. huuuuge night and day difference before and after, on paper and in performance/function. they even send you a full data sheet when you get them back on: before/after spray pattern quality, constant flow and pulsed flow before all work, and constant flow and pulsed flow after all work.

I actually just had them do the ones in my XJ a week ago, had them back in my hands 4 days later. installed them 2 days ago, and you'd think I did a brand new engine swap by the way it runs now. previously 1 injector had a "fair" spray pattern, and the constant flow had a 5.0% variation and pulsed flow had a 5.7% variation. factory spec is usually 3% variation max. after their work, they are now 1.0% variation constant, and 1.3% variation pulsed. and spray patterns are insanely improved

also, a large reason why oem injectors are you best bet is because our ecu's are very very basic and dont have a huge adaptability to parts that dont operate identical to stock. by using freshened stock injectors, the computer is very happy, and you will be too. aftermarket injectors have different spray patterns, different flow rates, different latencies, lots of different characteristics; and the ecu can't usually compensate perfectly for it all.
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Unread 01-18-2012, 05:31 AM   #5
Chrisp929
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Quote:
Originally Posted by motoxxxman View Post
you absolute best bet is to simply have the stock injectors cleaned/"rebuilt" by the best:
www.witchhunterperformance.com
$20 per injector for testing, analyzing quality, leak testing, multiple cleanings, re-testing, new o-rings/filters/baskets/pintle-caps. 2-3 day turnaround.

I've been using these guys for years, and every single time it's incredibly quick turnaround time and only top notch work done. huuuuge night and day difference before and after, on paper and in performance/function. they even send you a full data sheet when you get them back on: before/after spray pattern quality, constant flow and pulsed flow before all work, and constant flow and pulsed flow after all work.

I actually just had them do the ones in my XJ a week ago, had them back in my hands 4 days later. installed them 2 days ago, and you'd think I did a brand new engine swap by the way it runs now. previously 1 injector had a "fair" spray pattern, and the constant flow had a 5.0% variation and pulsed flow had a 5.7% variation. factory spec is usually 3% variation max. after their work, they are now 1.0% variation constant, and 1.3% variation pulsed. and spray patterns are insanely improved

also, a large reason why oem injectors are you best bet is because our ecu's are very very basic and dont have a huge adaptability to parts that dont operate identical to stock. by using freshened stock injectors, the computer is very happy, and you will be too. aftermarket injectors have different spray patterns, different flow rates, different latencies, lots of different characteristics; and the ecu can't usually compensate perfectly for it all.
im happy it worked out for you but i guess i would have to disagree with your comments about sticking with factory. I'm almost with you 100 % with respects to not deviating to far from factory as to not stress your computer. It makes sense. In many cases your remark regarding that is in fact gospel. But i think maybe in this case, that may not apply. I saw the video of factory 1 hole, vs neon/ford 4 hole, and i saw the spray pattern and cant imagine that a better spray pattern will in fact hinder anything on an otherwise factory XJ set up. It just makes to much sense to upgrade. I guess one can also use the stroker as an example. It uses upgraded 24lb injectors ( or higher like 26-28 lb) and it works even better ...
You could be right though. It's a sensible idea.
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Unread 01-18-2012, 05:47 AM   #6
cruiser54
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I've installed 3 sets of Precision's injectors with zero issues. I recommend them.
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Unread 01-18-2012, 08:02 AM   #7
motoxxxman
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Quote:
Originally Posted by Chrisp929 View Post
im happy it worked out for you but i guess i would have to disagree with your comments about sticking with factory. I'm almost with you 100 % with respects to not deviating to far from factory as to not stress your computer. It makes sense. In many cases your remark regarding that is in fact gospel. But i think maybe in this case, that may not apply. I saw the video of factory 1 hole, vs neon/ford 4 hole, and i saw the spray pattern and cant imagine that a better spray pattern will in fact hinder anything on an otherwise factory XJ set up. It just makes to much sense to upgrade. I guess one can also use the stroker as an example. It uses upgraded 24lb injectors ( or higher like 26-28 lb) and it works even better ...
You could be right though. It's a sensible idea.
the 4-hole injectors on ebay are a horrible idea, even though they are genuine bosch injectors. to be a 4-hole, the tip/pintle-cap needs to be noticeabley larger. I should know, that's what I bought as temp use injectors while my stockers were out. they went in ok, took a bit of extra force to seat them into the manifold. they seemed like awesome injectors for about 3 days, then gas mileage slowly started dropping, and idle started getting rougher, then it started to get minor misses under low rpm load. basically when the long term fuel trims were not set yet, it ran great, but soon as long term fuel trims began to set it ran worse and worse. then upon removal discovered the pintle caps were all crushed and heavily damaged, because the hole in the manifold is smaller than the pintle caps. which also distorted the 4-hole disc.

and to add a different concept, you say how you saw the 1hole vs 4hole. well keep this in mind: 1-hole means the injector is working as a normal injector. the pintle opens and sprays, and is not blocked by anything. the 4-hole is actually the exact same injector as the 1-hole, except it has a metal disc with 4 holes stuffed over the pintle restricting some flow, and is held in place by an oversized plastic pintle cap. which does relate right back to what I said in the above paragraph.

for reference, my stockers flowed 236cc. the 4-hole ones I got are identical injectors as my stockers but have the 4-hole disc, and they only flowed 204cc
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Unread 01-18-2012, 04:16 PM   #8
Chrisp929
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I guess ill save my money for a better mod. Thanks
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Unread 01-18-2012, 04:51 PM   #9
alexrule123
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I am running 4 hole mustang cobra injectors and my mileage has gone up. I have been running them for almost a year with no problems.
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Unread 06-28-2012, 07:11 PM   #10
jprischak
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I am having trouble with one of my precision auto injectors and they havent returned any of my emails. Do you still have their phone number, i have looked and cant find anything on their site but the email.
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Unread 06-28-2012, 07:25 PM   #11
tjwalker
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Mixed results with Precision Injectors. The vast majority are good. Some have had a bad injector or two (it can happen) and you MUST call them to resolve it. They don't seem to be great about responding e-mail, for whatever reason.....
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Unread 06-28-2012, 07:37 PM   #12
jprischak
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Does anybody know the phone number for them. The only thing i can find is fax and email

Thanks
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Unread 06-28-2012, 07:48 PM   #13
keepishop
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Quote:
Originally Posted by jprischak View Post
Does anybody know the phone number for them. The only thing i can find is fax and email

Thanks
The fax number is given as their voice numbers in confirmation emails. Give it a call and ring until you get someone.

They really do suck at answering emails.
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Unread 04-16-2013, 03:36 PM   #14
kevinofhardy
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Terrible experience

I purchased a set of these injectors from Precision Auto Injectors for my 99 Jeep Cherokee and he was really helpful when I placed my order and they shipped quickly. When installed they did perform as indicated. Smoother throttle response, felt quicker off the line. I immediately felt a harder start and when I contacted him I got no response. I tried calling and email for several weeks with no response. In the meantime I had removed my fuel rail and pressurized the injectors and there was a slow leak down issue that several forums had mentioned. I tried contacting him again but there was never a reply. We then installed the injectors into a project jeep we have since I didn't want them in my DD rig. After 2 days in this jeep one injectors lost all resistance and sprayed all fuel pressure into the cylinder and washed it. I cannot and will not ever recommend this product for the terrible service alone, but there is also a risk or ruining your engine. This was my experience with Precision Auto Injectors and Wojtek.
I purchased a set from FiveOMotorSports and they have been fantastic for only a little more.
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Unread 05-15-2013, 10:23 AM   #15
TheSnowman
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If anyone has the phone number number for precision auto injectors please post it or pm me with the phone nubmer. I ordered a set of injectors for my 90 XJ on April 21st, I recieved the injectors very quickly and was impressed with the service. After I installed the injectors, only 5 out of 6 were working. No big deal right, just exchange it! Well so far I have sent them numerious emails and posted messages on their site, so for no luck. I was impressed at first but the customer service is horrible so far. So much for testing the injectors before they ship them "We only rebuild and test our injectors on the newest state of the art ASNU fuel injection service bench"

So far jeep runs like crap with these injectors, granted its only running of 5 cylinders, hopefully I will see some improvements over the stock injectors.
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