How to tell a bad injector?

[Beau]

Ok guys,

I think I have a bad injector... A few symptoms are the following

- Takes a bit longer than usual to start 3-4 seconds of cranking. There is no air in the fuel, and fuel is not draining back.
- Slight miss when cruising at around 75-80 and call for a little bit more power
- No smoke at all...
- Slight vibration when cruising at 70+ and call for more power (I think it's the engine missing)

When I recently put the head back in, I had 8 injectors to chose from. I should have just put back in the 4 that I knew were in good shape but long story short, they all ended up in a box mixed up. So when it came to putting the injectors in I selected what looked to be the best ones and stuck them in. Since then, I've been having these slight issues and think it's down to a injector. I've ticked off everything else possible. Anyone else have anything similar problem wise?

I'd rather not just swap one injector here and there and replace randomly, so Other than getting them checked professionally, is there anyway to isolate a bad injector/test them?

Thanks!

 

[Chris]

You need them testing Beau. You can't tell by looking at them and in my experience these engines will run with quite poor injectors without showing particularly obvious signs. I had an 80 that was running OK, drove OK, did OK mpg. Took the injectors out, had them tested for a tenner whilst I waited and fuel was pouring through them. It should be like an aerosol spray can - a fine mist. Swapping them around even in a systematic way won't be like looking for a dud spark plug. You won't really see or hear the difference unless one isn't working at all. Once I'd had the injectors re tipped, I thought it would go like an express train. It didn't. It just used slightly less fuel and didn't have that white wispy smoke when idling. If you have a very poor injector, the bad news could be that fuel is getting into the sump.

Your symptoms sound more like starvation maybe rather than a poor injector

 

[StarCruiser]

As Chris says, testing's the way to go Beau. I had mine tested and two were pouring and the others just poor. Had them refurbished at around £70 each and refitted.

Different to Chris and unless I'm dreaming, I do think mine is going slightly better. But then it has been quite cold since and it always goes like a train when it's cold out.

 

[clivehorridge]

If you had a box of injectors, you could have a set tested without disturbing the ones in the engine.

Then do a straight swap with the refurbed set.

Best not to ignore IMO.

 

[StarCruiser]

I thought that but dismissed it thinking 80 series but now I look of course it's a 90 so that would be the perfect scenario.

 

[Beau]

Thanks guys, I kinda thought that might be the case. My theory is one (or more) injectors might be leaking so the lines after the injector pump aren't pressurized hence the few cranks to start. There is a slight mist of white smoke but only on start up?

I've been checking the oil, and it's remained the same, so no fuel leaking into the sump thankfully.

As far as refurbishing goes, do they just re-tip the injectors? I've dismantled a few injectors before and theirs nothing much too them. Is it possible just to buy the new tip ends and replace? like these http://www.ebay.com/itm/TOYOTA-HILUX-3-0-TD-1KZ-TE-NEW-INJECTOR-NOZZLES-SET-KIT-/281447338771 - though I'd probably want to buy off a good supplier or OEM depending on price.

 

[StarCruiser]

I'm sure you could change them yourself. Thing is, it needs to be done in a clean room environment or under diesel to prevent contamination, then tested to see that they're doing what they should, I.e. Spraying the right pattern and opening at the correct pressure, otherwise you've no idea if you've made them better or worse.

I considered mine to be money well spent.

 

[Chris]

It's more than just re tipping. They need to set the pressures at which they open and close, too.

 

[fridayman]

I did my injectors myself because I was curious about them. You will need new tips (probably), a set of injector shims, new washers, a decent pressure tester (I ordered mine from German ebay, don't get an Indian made Bosch knock-off), and a clean place to work. It's actually quite easy to do. Doing it yourself isn't the cheap option if you are only going to do it once though.

 

[Beau]

I did my injectors myself because I was curious about them. You will need new tips (probably), a set of injector shims, new washers, a decent pressure tester (I ordered mine from German ebay, don't get an Indian made Bosch knock-off), and a clean place to work. It's actually quite easy to do. Doing it yourself isn't the cheap option if you are only going to do it once though.

Do you have a link to the one you bought in Germany? I'm guessing the injector shims are used to increase spring pressure (opening pressure). Where do I get hold of these?

 

[fridayman]

Yes, the shims are to set the crack pressure. I got mine from Amayama. Take a look at item 120685280708 on ebay for the tester that I bought (after I wasted my money on one of the rubbish Indian made units).

 

[Beau]

Update - I took a chance and opened up/cleaned the 4 spare injectors I had lying about, and then swapped them for the ones on the car. The good news is, I haven't got anymore misfire/vibration at high speed so that's fixed that! I still have a cranking issue though as that's taking a couple seconds longer than usual. Acceptable but not 100%. So the journey to trace that down continues! Thanks for the help though guys.

I think that tester will be a good purchase when I'm ready to refurb my injectors!