Technical bravo on three cylinders

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Technical bravo on three cylinders

stega19

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hi first post bit of a big problem came back from holiday to find my fuel injector warning light on and my engine runnin on three cylinders.

phoned the AA who said it must be the actual injector itself which is gubbed. engine drops when you pull out lead to three of the cylinder but doesnt drop on fourth one. all hte electrics, spark plugs cables are ok and the pins on the harness beside the fuel rack all read ok.

Am i correct in identifying this problem as a fuel injector problem which could be solved by installing a new fuel injector and where could i get a used one cheap from as i dont like the idea of paying £130 for one
 
by checkin power to to injector do u mean the plug to the right of the fuel rack if so the AA guy measured them with his multimeter and said they were all ok.
 
he wrote on the form coil pack and ht lead ok, comp ok, pulse to injection ok , injection itself under suspicion.

I presume all the electrics were ok so if it is pulsing to the injector ok and yet there is no fuel going into the number 4 cylinder surely the fuel injector is at fault?
 
0 ohm resistance......injector open circuit needs a injector,2 min to test them all as plug is easily accessable(y)

In reference to pulse to injectors...this can only be reliably tested with a oscilliscope which I doubt the AA guy had.

Injector is about £78 from memory.
 
if its a 1.6 model the resistance of each injector should be 14.5-15 ohms and you can be pretty sure its an injector fault on a 1.6 because it always is. go to a scrapyard and remove one (or more for spares) they cost £5 each. make sure you check the injectors before you buy them, you want a good high resistance. any less than 14ohms and i wouldnt bother. i've changed so many of these things now, and sold many more, its an easy job you can do at home. (y)
 
jug said:
if its a 1.6 model the resistance of each injector should be 14.5-15 ohms and you can be pretty sure its an injector fault on a 1.6 because it always is. go to a scrapyard and remove one (or more for spares) they cost £5 each. make sure you check the injectors before you buy them, you want a good high resistance. any less than 14ohms and i wouldnt bother. i've changed so many of these things now, and sold many more, its an easy job you can do at home. (y)

Jug exactly how do I test the injector? I mean that usually here when I go at a scrappy to buy a part, it would be already removed from the car. So if the scrappy guy handed me an injector, exactly how do I test it before buying it?
Thanks.
 
TheCROW said:
Jug exactly how do I test the injector? I mean that usually here when I go at a scrappy to buy a part, it would be already removed from the car. So if the scrappy guy handed me an injector, exactly how do I test it before buying it?
Thanks.


each injector has 2 pins where the wiring harness connector attaches to it. you get your multimter out and measure the resistance across the 2 pins. it isnt a guarantee that the injector will work, it could be physically blocked up inside, but you do know that the electromagnetic valve is going to work well enough if the resistance is good. as the electromagnetic valve wears it loses resistance.
 
jug said:
each injector has 2 pins where the wiring harness connector attaches to it. you get your multimter out and measure the resistance across the 2 pins. it isnt a guarantee that the injector will work, it could be physically blocked up inside, but you do know that the electromagnetic valve is going to work well enough if the resistance is good. as the electromagnetic valve wears it loses resistance.
SOrry if it sound dumb as a question but I recently got my multimeter and I'm still learning :)
So when you say "measure the resistance across the 2 pins" do you mean to put each multimeter pole on one pin?
Thanks.
 
yeh its a 1.6 sx 99 model. few questions if i measure the resistance and they all read ok does this indicate a blocked fuel injector and not a worn one?

is their any other problems which would cause running on only three cylinders?

ive read some older bravos have different fuel injectors which models do i have to locate in the scrapyard to make sure the fuel injectors fit my car?

thanks
 
right, firstly getting the correct injectors, there are two types- 4hole and 2hole. the best way to make sure you get the correct ones is to remove them from an engine exactly like yours. there are 2 different inlet manifolds on top of the 1.6 engines, metal ones on the earlier models and black plastic ones on the later models. you have metal or plastic so simply make sure its the same on the car you remove them from.

if you tested the cylinders using the removing a plug lead method then running on 3 cylinders could also be a valve problem causing bad compression, or a worn piston ring, or a headgast leak only on that cylinder. a compression test will identify all of these. but i'd think its an injector, on a 1.6 it always is.

if the coil was causing the problem there would be a problem on coiled pairs, such as cylinders 1 and 4 or 2 and 3. so a problem on only 1 cylinder suggests the coil is fine. dont forget a HT lead failure or poor fitting can occur and also be the problem.

if the injectors all test fine and a compression test doesn't identify anything wrong then i'd think a blocked injector is a possiblity. but in reality a blocked injector is very very rare, even if you suck loads of crap out the tank, the fuel filter will block causing problems on all cylinders, but the chance of a particle entering the fuel rail and lodging in an injector is very low, especially if no work has been done on the fuel system. a build up of deposits on the injector spray head can occur but the high pressure of the fuel prevents anything from blocking a hole, the deposits build up around the the holes worsening the injector spray pattern, not over the holes preventing the injector from spraying all together..
 
Last edited:
Thanks jug the AA guy checked teh compression in the blocked cylinder and said it was ok, i am waitin on my new multimeter (£18 from halfords!) arriving then i will test the resistance of the injectors. I am expecting one to be seriously wrong if not i am not going to be happy lol.

i have the black plastic cover on my engine. so heres hoping one of my injectors is gubbed and i can fix the thing at last
 
ok measures resistance the far left pin read 0.8 the rest all about 15 - 16 does this sound correct. the far right cylinder is the one not firing so does this sound as if i have identified the problem?
 
Which type of injector did it turn out to be? Can you please describe it?
mk2 have Bosch injectors right?
 
ive not taken the fuel rail out to see only mesured teh resistance using the wiring harness its the mk2 one with fuel rail underneath engine so shoudl be bosch ones
 
stega19 said:
ok measures resistance the far left pin read 0.8 the rest all about 15 - 16 does this sound correct. the far right cylinder is the one not firing so does this sound as if i have identified the problem?


SUCCESS (y) (y) (y)

the far left pin 'should' be cylinder1 (far left cylinder on the timing belt side)


so now that you've found a dead injector you know what you've got to do this bank holiday weekend. go scrapyard hunting for an injector. dont forget to take your multimeter to test before buying.

i think all the injectors are bosch, its just a question of the 4 or 2 spray holes.

if the engine looks exactly the same as yours you can be pretty sure the injectors will be the same. obviously a model from the same year is a safe bet.

should be working perfectly very soon :D
 
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