Problems after new injectors

[robertE]

Hi, At long last I have sourced new injectors from USA as per this link https://linkprotect.cudasvc.com/url?a=h ... w,,&typo=1

(Had to ship them in via friends of mine in USA as company 'is not allowed' to ship these parts to UK!?!?!

After my garage (sorry I'm a driver not a mechanic!) fitted the new injectors, car runs fine when up to temperature, but rough when cold. Just after starting, for example, and driving out of the garage, foot on the clutch and engine revs to 3000 - 4000 revs . . .

Any suggestions? Thanks.

[Tuga2112]

Hi, At long last I have sourced new injectors from USA as per this link https://linkprotect.cudasvc.com/url?a=h ... w,,&typo=1

(Had to ship them in via friends of mine in USA as company 'is not allowed' to ship these parts to UK!?!?!

After my garage (sorry I'm a driver not a mechanic!) fitted the new injectors, car runs fine when up to temperature, but rough when cold. Just after starting, for example, and driving out of the garage, foot on the clutch and engine revs to 3000 - 4000 revs . . .

Any suggestions? Thanks.

IAC valve stuck open is a possibility. they dont really have an abit of failing. but they are 30+ years old now.

[Tuga2112]

i have also heard rumours that the isuzu injectors are oversized and put more fuel than its needed.
im not sure if that would make the idle higher, but i think that could be resolved with a CO pot adjustment or just waiting for the lamba sensor to start feeding data to the computer.

something else that controls idle as well is the screw at the top of the throtole body, but i would suggest you dont touch anything until someone else chips in.

[RonR]

Did your mechanic disconnect the battery during the fitting of the injectors?

The ECU may just need to re-learn it's settings for the new injectors - disconnecting the battery for a few minutes clears the "Block Learn" area in the ECU's memory.

Worth a try before resorting to more expensive options...

[robertE]

Did your mechanic disconnect the battery during the fitting of the injectors?

The ECU may just need to re-learn it's settings for the new injectors - disconnecting the battery for a few minutes clears the "Block Learn" area in the ECU's memory.

Worth a try before resorting to more expensive options...

Thanks for this suggestion. I'll give it a try. (I'd rather it re-learns its own settings, rather than me try to adjust things. It does settle down after less than 5 minutes, and then runs well, though I haven't taken it out for a good run yet.)

[Simon_P]

Did your mechanic disconnect the battery during the fitting of the injectors?
The ECU may just need to re-learn it's settings for the new injectors - disconnecting the battery for a few minutes clears the "Block Learn" area in the ECU's memory.

+1
you new injectors open slightly slower and deliver slightly less fuel (but hey they're cheap!)
"All fuel and electrical specs, dimensions, color, connector and physical appearance are 100% identical" I don't think so!

i have also heard rumours that the isuzu injectors are oversized and put more fuel than its needed.

I'd stop listening to rumours The fuel map dictates how much fuel is put in. The injectors were sized for this application ...which is their only application.

something else that controls idle as well is the screw at the top of the throtole body, but i would suggest you don't touch anything until someone else chips in.

No, the IAC controls the idle. The screw on the throttle body is just bypass air and a calibration for the IAC normal position at 20 clicks. Check it by all means using the instructions in the wiki (very simple)

[Tuga2112]

something else that controls idle as well is the screw at the top of the throtole body, but i would suggest you don't touch anything until someone else chips in.

No, the IAC controls the idle. The screw on the throttle body is just bypass air and a calibration for the IAC normal position at 20 clicks. Check it by all means using the instructions in the wiki (very simple)

what happens when the screw is set incorrectly and the IAC is not calibrated right ??

'd stop listening to rumours The fuel map dictates how much fuel is put in. The injectors were sized for this application ...which is their only application

do you know for a fact the Isuzu mapping is the same as the m100 ?

i seriously doubth that considering if you look at rockauto listings, the injectors for turbo and non turbo impulses have different suggestions with exception for the cheapest one ("ULTRA-POWER MFI31") which is the same injector marked for both engines.
the m100 parts guide provides a single part number. for both SE and NA

the "rumour" im refering to, is from a owner near me. who told me first hand he got impulse injectors from rockauto and found the car running rich after instalation. but after swapping with injectors from SJ, was running fine.
I did not see the isuzu injectors, and have no means to confirm he had received the right injectors from rockauto (or which engine he ordered). therefore informing others to be mindful its possible that injectors from rockauto will put more fuel than intended. if that affects the idle, thats something i wouldnt know...

i was originally suggesting "this may be related" but the further investigation actually leads me to think this "rumour" has some supporting evidence.

in future, when you dismiss my suggestions, i would appreciate a reasoning for them, as from your reply. i see no reasoning or evidence to to consider my suggestions unhepfull.

[robertE]

the "rumour" im refering to, is from a owner near me. who told me first hand he got impulse injectors from rockauto and found the car running rich after instalation. but after swapping with injectors from SJ, was running fine.

To be honest, the injectors I got from the USA were a second choice, as SJ took 6 months and still couldn't supply . . . If anyone can say that the SJ ones will sort my problems, I would be happy to invest the extra money and buy those . . .

(I haven't yet tried the 'disconnect the battery for a few minutes'. As I have the hood down, the battery is not that easy to get at!)

Thanks for suggestions.