Fuel Injector Information
 

So if the Multec 1's are in 89 to 91's.... what were in 85 thru 88? Are they Lucas?

I OHM'd mine the other day in hot condition and they were all 17.7 to 17.9

Should I check them in a cold state? What should they read in comparison to when theyre hot?

Ive been considering changing injectors for a new set...

When engine is cold, (sits overnight)... it fires on the first touch of the key.
After its warmed up fully, if you try to start it up within a few minutes after shutting it down, it will fire right up. BUT, if you wait any extended period of time, it takes 2 sometimes 3 tries and more crank time than it should.

This had been going on since I bought the car and before and after all the full tune up, new fuel pump, filter and coolant temp sensor etc, etc. (The car runs much better than when I bought it for sure....) but the hard restart condition persists when hot after sitting.

So the only things left would be the FPR and injectors.... How do I verify?

My 86 has Lucas injectors. Don’t know if they are stock or have been replaced along the way.
Mine all OHM’d exactly what yours did 17.7-17.9
If mine has sat overnight it takes 2-3 revolutions to start but if the car if hot it is like a 1/4-1/2 of a crank. It lights up real fast.

I think 85-88 were Bosh 1.

Might check your cold start injector? Wonder if it's not firing under certain conditions?

Pretty much the opposite as mine....

Doesn't the cold start injector come into play when the engine is cold, and not hot? Sounds reasonable.... but I really am not sure.

I think you are right. I read the other reply and confused his issue with yours!

There is no such thing as Bosch1 or Bosch3 for that matter all the injector types are EV something EV1 EV6 there is no EV3

I would check for codes, fuel pressure, and timing. Scanner would be handy. You should be running regular not premium. If nothing showed I would try decarboning.

My 89 does exactly the same thing. I replaced injectors, FPR, even the ecu, but made no difference. I read an article somewhere that at least on the 89’s, it was a programming problem from the factory and a common one at that. It can be fixed by altering the program. I have changed some things in my ecu by using trunerpro rt and an ostrich, but I don’t know enough to work on that problem

:iagree: (sorta) -- pretty sure when folks refer to boschIII's, they are meaning the third design, which are indeed EV6 style injectors. pretty sure EV6 injectors went through several design revisions over the years. :rock:

I think timing could be an issue.... Today I hammered it a few times and could hear pre ignition/ detonation under heavy load. I actually use premium all the time....

For anything other than the most minor change it would get a new EV engineering series number.

Ok, so what injectors in my 86 L98???

You could read the part number off them. Being over 30 years old how much does it matter now as the odds of finding new ones is probably zero.

It doesnt matter... Im wondering if they are Lucas or Multecs... Im not trying to find the same ones.... Point is, I read that the troublesome ones were 89-91.... If I dont need to swap these, I wont. If I need to, then Ill get what I need as a replacement probably from FIC.

Post a picture of them

Heres one

It is pretty simple if it runs good do nothing if not determine why and fix whatever it is. Multecs are made by Rochester and historically have a smooth body with no reduced diameter section as shown in the pic. You should be able to take the connector off the injector furthest to the right in the pic and get a part number to google.

If you read my first post then you can see I have a start issue when hot after sitting for a while.... THATS why Im considering new injectors and after all the failures I see with guys and their Multecs, I thought Id check a few things out. Ill see if I can get that part number... thanks.:cheers:

FWIW, here's a pic of the GM multec vs EV6/3rd design injector (commonly known as boschIII).
https://www.thirdgen.org/forums/atta...difference.jpg

on the subject of boschIII's, here's a pic of the 3 current bosch designs --

https://cimg4.ibsrv.net/gimg/www.cor...52e3dd4c0f.jpg

EV1 or first gen bosch were used on early TPI cars. not sure when GM switched (backwards) to multecs. considering the technology at the time, original EV1 bosch injectors were, and still are a good design. I don't know who holds the design patent, but EV1 injectors are licensed and currently manufactured under various nameplates. not 100% positive, but i'm thinking there are 4 major EV6 designs. don't know the original EV6 applications, if any, but 2nd, 3rd, and 4th designs are commonly used. aside from size and design improvements, the major difference with the original bosch injectors are the number of fuel discharge ports - EV1 - single, EV6, 4-hole discharge port.

https://cimg9.ibsrv.net/gimg/www.cor...0fd2a81a13.jpg


:rock:

Thanks Joe..... I was able to cross reference the number stamped on the injector itself and the best I could come up with as far as brand, was GM or AC. They were referred to as both. Other part numbers were:
217-231
17111418

The actual part number stamped on the injector is 5235211

Ok, so it says there the resistance is 12 ohm.... I assume that is the cold condition reading.? I have only checked mine hot.

:cheers:

That (5235211)sure looks like a AC Rochester part number.

That’s a Lucas injector. Same as what I have.

Have you checked the resistance on yours? Is it 12 cold? What about hot?

fyi that 12 ohm......that is a Ford/Bosch 14lb injector. Apples to oranges.

You know i never did. They were all in the upper 17s warm.

Ima' check mine when I get off work tonight, just so we have a cold/hot base line for this type of injector. Im also gong to try changing the timing a couple degrees too. Im at 5300' altitude....

Not exactly true. I have had 4 port EV1 injectors. The early FMS 24lb blue tops and orange yellow top with a BRASS base 19 lb were EV1 with 4 holes/ports as I’m sure many else were.

not doubting you, but I can't see how an EV1 injector can have 4 discharge ports due to the characteristic design of the injector nozzle.
**************************************** *******************
damn, it took a while, but I did find this...

https://cimg3.ibsrv.net/gimg/www.cor...f750810ebd.jpg

guess you learn something new everyday - :thumbs::thumbs:

Ok you made go deep into my toolbox from almost 20 years ago from my push rod 5.0 days. These are OE 93-95 19lb.Lightning Injectors rumored (i cant prove it) to flow 21lbs. These were also marketed as FMS 19lb injectors (allegedly balanced). If you had a speed density car that was modified these were the ticket. BTW all 8 cost me $60.00 new!

that first injector is a ‘pintle’. Decent for fuel economy in the day but not a ‘performance’ injector.

I have the EV1 style in my 86 late (aluminum heads). I was thinking of replacing them with the newer style injectors with the multi hole ports as I read all over this forum that they give a better idle etc. mine ohm out fine, and I removed all the filter baskets etc as I was originally going to refresh them myself. the car ran fine as far as fuel delivery goes, was a bit hard starting but with 160K a couple of cranks doesn't surprise me and doesn't bother me. I was set to upgrade but now budget concerns are kicking in again so I may go back to the originals. I can get them flow tested after I replace the parts pretty cheap.
I am starting to think that before I upgrade my L98 to a full roller etc, an LS swap may be more fun in the long run.

Update: So just for the record, all of my injectors ohm'd between 16.1 & 16.5 tested cold.:cheers:

Here's my injectors while working on my '87:

https://cimg3.ibsrv.net/gimg/www.cor...1c3df42da6.jpg
Uh, no, I always clean my workbench.


I have no idea if my PO installed these or if original. They look similar to yours, 81c3. They are resemble the EV1 except for the pretty color and different end.

Note: where the orange washer is near the tips, that's where the orings go, hadn't gotten around to that in the pic. :yawn:

Same ones in my car kael

Yes

Premium is not necessary in the low compression 86 L98. Just tossing money out the window.

Multitec's

If you're going to keep the car, buy a set of Bosch III's from FIC.
Replace the fuel filter and run the car before changing the injectors to prevent contamination after replacing the filter.
Open and inspect the FPR. If there is fuel on the vacuum side replace the diaphragm.
You can check for fuel presence by pulling the vacuum line and checking for fuel.

My experience with the 86e was she ran better overall. Idle and throttle response were improved. I didn't notice a power change as much as she ran very smooth afterwards. I did add and adjustable FPR cover that allowed for some max pressure adjustment that helped throttle response greatly.

:cheers:

Thanks Coach! The only question I have though is that you say the injectors are Multecs.... Everything Ive read so far and part numbers are saying Rochester, AC, GM.... Seems the Multecs werent used until later MY.... What gives?

On another note, talking about the cold start injector.... When I start the car cold, it fires up in a 1/4-1/2 turn of the key.... Idles as it should and gradually comes down to 650-700..... Now... while the engine is cold, if you even think about blipping the throttle or giving it gas it stumbles terribly.... Once its warmed up and the idle settles at normal rpm, it runs perfectly. Is that cold start injector related or something else? Not a big deal, because I dont jump in and drive anyway... I always let it warm up before driving.

Wouldn't it be better to scan it with different grades of fuel so you can see if the it is necessary and if the station you think is good is really selling the good stuff or not?

For $50, if it is old, maybe it might be a good idea to replace it when you are doing injectors just so you don't have to go back in? IDK how difficult it is to do but I have a HSR which is easy. On my Superram, it is more difficult so if the plenum comes off, the regulator gets changed. How difficult is the job? I can't remember anymore.

Either way, they are kinda of old and a reman set is so cheap, I'd do it just to get the crud out. See image below.

I'd do a couple of things. Send the Cold Start Injector out for service since they do have build up. Next, check the coolant temperature sensor. Scan it so you know what the ECM sees and hit the sensor with an infrared thermometer so you know that it is somewhat consistent. What you describe could be the injectors not doing the job right or the temp sensors are not quite right or the IAC isn't as good as it should be. If it is the IAC, the cure is to clean it and if that works, life is good. Take the TB off. Remove the top plate, the IAC solenoid and the IAC housing. Clean passages. Clean the IAC pintle with a gentle spray of brake cleaner and GENTLY wipe the pintle off. Reassemble with fresh gaskets. Also, check the IAC counts with the scanner once it has reached stable operating temps and everything but the motor is off. Should be around 20 to 30 counts.

https://cimg6.ibsrv.net/gimg/www.cor...e41213a3af.jpg

Premium or 91-93 octane is by design harder to ignite than Regular 87. The lower octane fuel ignites quicker which aids in start up. You want to use the recommended fuel. The stock L98 all had low enough compression they could use regular. Using premium can cause delayed starting, engine will start but not as fast as expected. LT1 had a jump in compression and premium was recommended.

So I already did replace the coolant temp sensor when I flushed the system. I pulled the IAC valve and cleaned it as well. I cleaned the throttle blades, but not any other passages. There was really not much to clean....

Dont have a thermometer nor a scanner... :(

It does sound like it is high and the ECM is compensating. Either way, a scanner will tell us what the command idle speed is and what the RPM really is. It does sound like there is extra air coming in and the ECM is slowly trying to get it to whatever the program wants.

Yea, I'm not certain... Its only when I first start the car and its dead cold.... If I never touch the throttle, it operates perfectly..... you would never detect a problem.... it runs, idles and slowly decreases rpm(about 1000/900 down to 650/700) as it warms up as it should. Jump in and take off,,,, everything is normal.

Im going to check the timing tomorrow and see where its at. This whole thing started the other day when I noticed some pretty bad ping under heavy load. Not from a dead stop, but after Im cruising pretty well, I hammed down and it pings.... never noticed before.

My guesses are timing, injectors, FPR, or now that everyone is saying dont use 91 octane, maybe the gasoline.... this is exactly contrary to how I understand higher octane gas works.... but its worth a fill up of 87 I guess....

Car has 31 years on it, but only 35k miles...

If I understand you correctly, you are saying YOU didn't detect anything amiss. It doesn't tell me if the ECM compensated for it or not.

Could be bad gas or dirty injectors or FUBARed injectors. Hard to say at this point. My understanding is that the Multec injectors don't tolerate ethanol well. Coils are fuel cooled and ethanol eats away at the insulation. Run the gas down to the end and fill up with fuel from a good source or another place. See what the scanner finds.

Higher octane resists auto ignition better. Not totally sure about the increase in starting efforts.

Base timing was off at about 8*.... now at 6* BTDC... Havent had a chance to test drive.

What spark plugs are you guys using in an iron head L98?

FWIW, in my 85, i'm running NGK G-Power Platinum Spark Plugs, number UR5GP/3547. no issues. :rock:

BTW, my base timing at 7°, and I flip back and forth between plus and premium. no reason, just something I do, and to be honest, I can't tell any difference - :crazy:

Off by 8? That is a lot.

Edit: Never mind. Off by 2 isn't too bad.

You can use NGK or Delco. I wouldn't bother with the Iridium ones that cost a bunch. Middle of the road is fine. Toss them next year.

8* is perfect. Mine runs better all the way around at 8 vs 6.
NGK is what I run in almost everything.
Run spark plug: Part no. UR4, stock no. 6630 for an iron head.

Maybe later after he gets this sorted out but till then, I'd run stock values so we have less variables.

Well I hope the 6* helps.... Its pinging bad under load at 8* Like I said, not from a dead stop or under normal driving conditions... that's whats funny, car runs excellent and has great throttle response.... starts well cold, but the 2 things I am having an issue with are the ping under load when I hammer it while already moving.... then the harder than normal restart after it sits and gets heat soaked. I'm leaning harder towards injector related. The other thing I thought was maybe ICM..... for the harder restart issue.

Also, I am at 5300' altitude if that helps determine anything for where the timing should/could be.

I'm not a fan of turning up the timing on the distributor. I'd rather have it done in the ECM. Either way, I doubt 2 degrees will do that much so as to have it ping. Sounds like a fuel issue but check everything out with the scanner. See if the O2 is lazy and the ECT is right.

I dont have a scanner or access to one.... wish I did.

Update: So I took it out for a spin tonight and no pinging at all... I cant imagine how 2* made that much difference..... but I TRIED to load it to and it wouldn't ping.

I honestly expected the power to feel less than it was, but I could tell no difference.

I also pumped $25 of 87 octane in the tank, but after my test drive and on my way back up to the house.

The only real difference between tonight and a couple days ago was the ambient temps. Tonight is about 42* The other day it was 77* The coolant was the same though around 160-165*

Before setting the timing today at lunch, I did not check or clear codes. After I was done setting the timing I did disconnect the battery for a minute or two as described in the FSM. Is it possible I had a code stored that was affecting timing and now its not?

Damn it, I hate an intermittent issue.... or one that fixes itself... Im still planning on changing plugs to a solid copper core I think, and I still want to do the injectors.... if nothing else to have better technology.

I was looking at Ecklers and the FPR diaphragm kit is $200. Can that be true? Seriously???

The DA (air) change affected you car WAY more than 2* timing. If you go back and do the math, what time you were driving, and figure out what the DA was both times i bet it was a 2-3000’ difference. I’ll bet you dollars to doughnuts thats your ‘intermittent fix’.

Also instead of pumping 87 into the tank find some pure gas (ranges 89-91) run a couple of tanks through it and report back.

Run the plugs I posted and gap them down to about .040

Ok, what is DA? I dont think I can find any gas without ethanol in it.... if thats what you mean by pure gas Its winter blend time here in Colorado.... right now Im using NGK 3547 plugs...

1) DA= density altitude
2) I have no clue what those plugs fit but they are no where on NGK’s catalog for your car.
3) Acorn Gas and South Shore Marina in Pueblo.......don’t know if thats close to you.

So as far as the DA.... I assume nothing I can do there....

That station is about 45 miles from me.... :(

ugh facepalm.....corvette owners on forums! no you cant do anything about the weather but you can figure out the DA for both days and get a better understanding on why your car ran differently on the the two days you spoke about.

Sorry, Im not as smart as you I suppose.:hide:

I think your bigger concern should be to find a gas station that has fresh gas. IOW, avoid the Mom & Pop stores. Get something with heavy traffic instead of a car every 2 hours. Ethanol has been talked like it is asking someone to take a dump in your tank. If you were having your boat sit at the marina in the water all day long, it might be an issue. Otherwise, IMO, just get fresh gas and forget it. I used to live where they had no ethanol in 93 octane. Didn't seem to help mileage much, if any at all.

As to plugs, get whatever NGK recommends. Install them. Run the car and night and spray a fine mist of water around the wires to see if they are leaking.

Yes, I know about not using Mom & Pops.... I use either Conoco or Shell. Our choices are 85,87 or 91 octane. Traffic is very heavy at both stations... Im 11 miles from the Royal Gorge Bridge... We have a ton of tourism pretty much year round.

For the plugs why is everyone stuck on NGK??? Just curious... Why not use the AC Delco R43TS ???

My wires are brand new Taylors

Then you should be fine as long as the ECM doesn't pick up pinging to use whatever you want.

You could. Just happens to be what is common.

OK. As long as they are not leaking.

I assembled the boots to the plugs with dielectric grease as well at the cap towers.

My knock sensor was also replaced when I did the coolant flush and torqued to 14lb/ft so I believe thats ok...

Just seems strange that it didnt do it at all last night... I deliberately tried to load the engine even on the same stretch of road!!! :smash:

What I meant was the the ECM will tell you if it is ok once you hook up a scanner. Say you see a lot of knock at 85, switch to 87 and 91 and see which one gives you the least knock. If 87 and 91 are the same, stick with 87.

Its ok. We all want to help everybody and have good intentions! :cheers:

if you cant get pure gas Shell 91 in your area is the best you can buy.

People buy NGK because they are a premium plug that just seem to work in any application.
AC R43TS is cheap junk made out of the Autolite factory in China. They are not what they were 20 years on back.

So I saw a few guys saying that a lower octane fuel is more volatile and I should use that instead of the 91.... I always thought the 91 was the most ping resistant... then some say I wont need it with a low compression L98.... I have iron heads, not aluminum... maybe thats why? Sometimes shit get confusing...

What did your manual say

You mean Lucas? Or EV1?

I noticed the EV1s had rubber boots on the end, mine don't, they are metal with a inverted conical end.

The plugs i suggested are for iron heads.
91 will be the most ping resistant. As for reg fuel out of pumps Shell V-Power will be the best you can get.

Lucas

Glad someone else brought this up. My understanding is that 87 octane is more volitale and prone to pre or post detonation and therefore pinging. I would think using it in this instance would compound the problem.

FIC = Fuel Injector Connection, correct? Is this currently the best place to get a set of 30lb? If I'm way over budget already can I go with the rebuilt red ones for $200?

I'm going thru Minneapolis this week, could pick up a set at TPIS listed for $425. They look different from the FIC ones.

I'm using a Miniram.

https://cimg5.ibsrv.net/gimg/www.cor...f0b20a8e1f.jpg


https://cimg6.ibsrv.net/gimg/www.cor...5508579594.jpg

I'd go with rebuilt ones. I have unless there is some reason to go with brand new.

They should. The FIC red ones are the later design compared to the TPIS reddish-brown ones.

Miniram won't know the difference.

Identical prob here. There is another thread I started.
Still have not pulled the plenum to do the injectors to see if that's it.