Thinking about on my 1989 TPI cars, the two I presently have, both I've replaced the fuel injectors. They were the original Rochester Products (RP) Greenish/gray units. I replaced them with new Delphi versions which dropped right into place.

They were sourced from FIC, looked good, and function perfectly. Cars deliver torque again! Here's a link: https://fuelinjectorconnection.com/c...l-injector-set



On my previous 6.3L GTA, I replaced the injectors for a slightly larger-sized version, and never had any troubles. On a Corvette with a similar-sized engine, same thing - had larger injectors, so the "RP" injectors were long gone.

On the other two, one was replaced around 52,000 miles. Other had about 5k mi. Both are 1989 models, and within about 18 months of one another.

The greenish/gray RP injectors, due to their design, are suspect at best these days. If your car has an issue with starting once warm, or taking a long time to start, regardless, check the ohm resistance in each injector (easy to do, with TPI still in-place).

So... Have you had to replace your injectors on your 1989-1992 Third Gen TPI Car? If so, why / what were the circumstances?

 

Yes, many years ago (2005?), the OEM Multec injector coils started to short out. No fun having the engine shut off at 70 MPH.

Replaced with a set of Bosch JY injectors and re-tuned. Cleaned them myself and haven't had an issue since.

RBob.

P.S. note that I didn't vote in the poll as there isn't a selection for replacing them with used injectors.

 

My 89 350 car came with already replaced Bosch IIIs. Never liked how it ran and tried everything else, so assumed it was in the injectors. Put in a new set of IIIs from SouthBay and... it still kinda sucks at idle. WOT is fine and crusing seem OK, but my BLMs are way high at idle, around 160.

I'm considering swapping to another set of injectors unless someone can tune these right for me.

 

Hmm i was under the impression that the early delphis we not so great with ethanol.

 

It's not just the Multecs, any of the stock injectors after nearly 30 years are going to be worn out or likely somewhat less than optimal.

Delphi is awfully proud of their new Multecs. There are tons of clearance priced Standard injectors out on Ebay. I haven't paid over $200 for a set yet. In all cases the new injectors have run better than the originals. That said I'm still running the 120k+ mile OE injectors in my Formula and it runs just fine. I can't help but wonder if it could run better with fresh injectors, but for now I can't see replacing them.

 

Delphi injectors are not Rochester Products Multec injectors.

I'm okay paying the $400 for those. Bosch III injectors look like a plastic toy, when compared. I've seen both in person.

 

The one's I've used are good for up to 15% ethanol. But do see they backed the written spec to 10% which is what most pumps dispense.

I didn't have a problem until I had a problem. 2c.

 

Replaced mine about 10 years ago. Accell 23# units from Jegs. No problems since. (knock on wood)

 

The first generation Multitecs had a questionable reputation across GM car lines. The resistance typically drops as they fail, and sometimes intermittently short out and kill the engine (as mentioned). My personal experience is that they need to be within 0.01 ohms of each other cold (with a good DVM). Any variation above that says they are on their way out. I can even here the difference in them as they act up (they get quieter), associated with random misfires.

 

GM spun several of their parts divisions, Rochester, Packard, Guide, etc into Delphi. Later Delphi was spun off to be a separate company from GM. Rochester became part of Delphi in 1995. So yes, Delphi injectors ARE Multecs. They may be improved, but I wouldn't bet that kind of money on a maybe.

 

Interesting. I knew Delphi absorbed a bunch, but then "let go" of a bunch of brands and such, about 8+ years ago. Maybe longer.

At any rate, the new injectors are designed to run with ethanol blended fuels, which the grayish / green Multecs were not.

As I bought another GTA which has Multecs still installed, I wonder how long til they crap-out (technical term) for biting the dust when subjected to ethanol blend fuels? I don't believe the car has been exposed to e10 fuel yet. Yet...

 

I would use ethanol free gas if it wasnt 2 hours away. But I found videos on youtube of people separating it out from pump gas. Apparently you just fill up a 5 gallon jug of E10, dump in a liter of water, mix it up real well, let it sit a couple hours. I guess as the water is going down to the bottom of the jug, its pulling down the ethanol with it... not sure. Turn it over and let the water/ethanol mixture at the bottom drain out.
You should empty out your liter of water, plus another half gallon of ethanol (i think the math is right). And at the top you have 100% gas. Minus a few octane, so make sure you get premium if you do the experiment.
I tried it on some old gas and it works great in lawn equipment. But im a little.... i dunno.... if i wanna put 4.5 gallons of something that had a liter of water into a vehicle's gas tank.

 

Injectors can play tricks on you. Some reasons for me...

If they don't ohm cold properly (or short out) they need replacing.
If they don't ohm hot properly (or short out) they need replacing.
If they ohm cold and hot and click but are clogged they need replacing.
If they ohm cold and hot and click but constantly dump fuel into the cyl... you guessed it.

Otherwise they are perfect little devils!

 

I replaced all 8 back in 2009. What a pain in the a$$! I too got mine from that same source. I have not had any issues since.

 

Stock injectors are TRASH. Southbay's make me run so much better and on the stock tune.

 

Multec injs had problems even back when they were new. Always saw cars in the dealer getting them replaced.

 

Yep. I did the service writer thing at a chevy dealership back in the early 90's. I can't count the number of Camaros we replaced injectors in....... (under warranty)

 

Got my 89 LB9 in February, 117,000 miles, three owners. Engine largely untouched but ran more or less fine.

Started in on refresh trying for minimal work.

Problems arose and started chasing them.

It is now November and I have changed everything except the heavy parts. Including the stem seals, springs, and timing set.

I changed my injectors as part of an effort chasing an idle and running stumble issue that arose shortly after I did a Seafoam treatment. I thought I had clogged the baskets and since everyone rags on the Multecs I thought why not. I swapped in 19lb D3s and it ran a little better but the stumbles were still there. I then found shorting spark wires, loose timing set, and did the seals,springs anyway.

The car ran nicely except for the remaining high RPM, heavy throttle power loss that was not there in February. I noticed my BLMs were 160. After many discussions, I was advised to try the 22-lb and it worked great. BLMs were good with stock fuel pressure but the high rpm issue was still there.

Tried a new tune and ECM no luck. Went from 89 APYY memcal flash to 87 ABUS memcal flash and that solved my problem somehow (my car is an 89). Powertrain runs great but I'm in the hole some significant coin from all the parts. Forget my time and effort, I'd be broke!

 

Mine is an '88 L98, but I've long suspected injector issues--idle is never quite smooth, and BLM's are way high (160) until off idle, then they begin to drop. An awful lot of people have used the Bosch III's, but I've heard good/bad about them, some say they're drop in, others say they're less than optimal unless you're willing to do a tune.


Are the Delphi injectors definitely better? I don't mind paying more if I get more, but otherwise, I want to do it right, as inexpensively as possible.

 

No tune on the Delphi. Smooth idle. No issues.

 

I know it was nearly 3 years ago I wrote on this...but I’m now chasing a suspected busted fuel pressure regulator diaphragm...seems to make sense to replace the injectors at the same time, and I’m sold on the Delphi units...will I need to order O-rings for the injectors as well, or do they come with them?

 

The injectors came w/ O-RIngs and are plug n play.

I did buy a box of each of the two sizes of o rings needed for the fuel lines and TPI Rails. They can be had at AutoZone. I can get part numbers, if needed. I replaced all o rings I could get to reaching.

 

For the rails get standard motor products sk24 from amazon .