Hello all, I was wondering if someone could tell me the procedure for testing installed injector's ? After doing my tune-up the firebird run's extremely well except for a small (at idle ) stumble there doesn't appear to be a vacuum leak so I thought one (or more) of my injector's might be going south.
One other question, Is there any reason (other then previous owner's cheapness) that I would have seven injector's of one type and one injector (#1 cylinder) of a different type? Thank's ......SR

 

As for testing injectors while they're in, I have no clue.

I'm guessing the previous owner went cheap like you said and only replaced the bad injector instead of all 8.

Sorry I couldn't be of any help.

Dave

 

The only thing you can check while they are still in the car is the resistance (ohms). You won't be able to properly check the flow pattern or rate while they are still in. Spark plug condition though can be a good indicator if one cylinder is running lean or rich though.

 

IROCKER".... The only thing you can check while they are still in the car is the resistance (ohms). "
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The plug's looked fine when I changed them out , Nice even tan colour. What is the resistance supposed to be? How much of a difference between injector's is O.K? thank's again.SR

 

When we tested my injectors anything above 17ohms was good. I had 6 injectors reading under 5 ohms ... B A D ... ended up replacing all 8. What year is your car ? That has alot to do with injector longevity and quality.

RP.

 

In 1988(I think) General Motors started using Rochester Multec fuel injectors. These injectors are notorious for failing. The problem with them as explained to me is that the coil comes into contact with gasoline as part of the design. The protective coating on the coil wears out after a while and effects the resistance of the coil, thus effecting performance. This can happen overnight without warning. Mine were so bad that it caused my cars idle to loop. Only 3 of my injectors were within spec. Naturally I called gm to get a price on replacement injectors and hit the roof when I discovered it was going to cost me $1700.00 for the new injectors. Thats when I found out about Cruzin performance. I talked to the owner and he gave me the info on the Multecs. So i purchassed a complete new set of Acell injectors from him for 229.00 US. By the time it got to my door with exchange and all the other good stuff it cost me 450.00 Canadian. The cheapest I could find them here was 499 + tax or $570 Canadian. So I saved $120 bux by ordering them stateside.They appear to be working fine although I'm still chasing down an engine miss, however this miss was present before the Injetor swap. For less than 1/3 the cost of using New Multecs I'll take my chances.

 

As far as I know the Multecs were from 1990-1992. Rick at Cruizin sure knows his stuff on injectors. If you guys have troubles give him a call and you will get it straight.

The Multecs (what I have) are garbage and GM should replace them free of charge but of course will not. Next set I get will be from an LT1 -- very solid design, very reliable.

RP.

 

Exactly...mine all tested fairly close to each other in the range of 16-17. You should test them when they are cold and when they are warm. The overall resistance will go down a bit, but they should all still be fairly close to each other in their readings.

And just an FYI, I've got Lucas injectors in my car and Cruzin Performance tested my set, without even cleaning them, to be within 2% of each other...and that was after being in my car at least 4 years. So I fully endorse Lucas.

 

Thank's guy's ,Ill be checking them tomorrow(assuming it stop's raining). Like I said the car run's great except for that small stumble. If the injector's test ok I'll have to look elswhere for the problem.
Thank's again.....SR

 

Well I checked my injector's today and the result's were 7@16.5ohm's and one (the oddball) at 16.3 ohm's. So I'm guessing I'll have to look somewhere else for the reason for my minor stumble at idle......SR

 

Have you checked the throttle position sensor for any flat spots ? Usually when they are on their way south they start to act up on the most well worn spot which is the 'low rpm' side of the contact patch or where the throttle spends most of it's time. Thing is I forget what my readings were when it was last tested -- ohms ? Volts ? Not sure what a solid TPS reads like ? Does anyone else know ?

RP.

 

No,I haven't checked it but I will,I'll do a search on the TPI and electrical board's for the procedure........Thank's for the suggestion.......SR

 

hey snowracer
What I have found very often is to do an injector flush. Alot of people have their reserves and opinions about doing this but 9/10 times it works wounders.
just my two cents