Modern fuel injectors
- Thread starter James0
- Start date
PSH
PCGB Member
Funny, as I have never had a rough idle due to AFR, it can be lean of rich within reason and the idle remains solid
My AFR reading has never been rock solid, it bounches around by 2 or 3, my son did tell me why but I can't remember, it might have been due to where my O2 sensor is positioned. I do have the ability to data log the AFR but have never had a reason to do so.
Pete
My AFR reading has never been rock solid, it bounches around by 2 or 3, my son did tell me why but I can't remember, it might have been due to where my O2 sensor is positioned. I do have the ability to data log the AFR but have never had a reason to do so.
Pete
PSH
PCGB Member
Guides seem to vary... Bosch states no closer than 8 inches to Turbo and 24 inches from tailpipe which mine fits into nicely. It doesn't really matter where on a pre cat car, needs to fit in as stated above. Needs to have the wires upright, between something like 10 - 2, must be the top of the pipe to avoid condensation and any joints between need to be fully sealed. I use a heated o2 sensor so no need to be closer to the engine.
PSH
PCGB Member
blade7 said:
I could be wrong but pretty sure that later turbo's had a CAT, I seem to recall a friend with an 89 complaining about the cost of one from Porsche. There certaimly seems to be plenty of suppliers out there selling CAT's for the turbo?
I've never really paid it much attention having none fitted to the 86 so stand to be corrected if wrong. Perhaps others can say if they have one and for which year might answer the quedtion?
Pete
Some had them but they don't have to have them for the MOT. I can't remember what year they would be mandatory 93?
Mines got a hollowed out cat (not by me, I'd imagine that was a dirty job), obvs off a later car. The S2 exhaust in my garage (from when my engine was 16v N/A) has a cat.
Mines got a hollowed out cat (not by me, I'd imagine that was a dirty job), obvs off a later car. The S2 exhaust in my garage (from when my engine was 16v N/A) has a cat.
A good friend and exceptional tuner (he maps BTCC cars, etc) pointed out that the low flow at idle and the position of the WB bung on my car meant it wouldn’t be massively accurate. He also said not to worry about it jumping about a bit at idle either, as long as it’s right when it’s under boost and higher flow.
My wideband bung is in this generally accepted position:
https://www.lindseyracing.com/LR/Parts/WBO2LOCATION.html
My wideband bung is in this generally accepted position:
https://www.lindseyracing.com/LR/Parts/WBO2LOCATION.html
I'm a little concerned that being an injector for a 16 valve car, the spray pattern doesn't fire directly onto the inlet valve, but to either side.
A quick mock up with a 30 degree paper template suggests a lot of the fuel wil hit the walls just before the valve .
It's batch fire so there will be fuel on the back of the valve.
Just not sure how critical firing straight at valve is. I'm annoyed I didn't think about it
A quick mock up with a 30 degree paper template suggests a lot of the fuel wil hit the walls just before the valve .
It's batch fire so there will be fuel on the back of the valve.
Just not sure how critical firing straight at valve is. I'm annoyed I didn't think about it
blade7
Well-known member
The factory location in the downpipe, is for a narrow band 02 sensor. You should be careful who you speak to. Plus if you were using a engine management system that can use info from an 02 sensor, having it mounted near the tailpipe probably isn't the most effective place.PSH said:
PSH
PCGB Member
I've never really studied these things James but do know that if a head is polished too much it will affect the way that the fuel atomizes and thus lose power. If it's that susceptible to how the fuel burns then perhaps having the correct pattern is also very important. Hopefully, someone with more knowledge/experience of such things will be along soon to give a more informed answer.
Pete
Pete
Well after lots of buggering about I've decided to take it on the chin and ditch the new injectors.
So if I can be arsed I'll eBay them .
I think looking at the spray pattern I'm a bit paranoid of bore wash from spraying straight past the valve rather than hitting it.
It'll probably be fine but it'll always be in the back of my mind
The car did drive very nicely with new injectors, although I only tried off boost and Idle was a pain to get right.
So Next!
Siemens as I probably should have done in the first place.
So if I can be arsed I'll eBay them .
I think looking at the spray pattern I'm a bit paranoid of bore wash from spraying straight past the valve rather than hitting it.
It'll probably be fine but it'll always be in the back of my mind
The car did drive very nicely with new injectors, although I only tried off boost and Idle was a pain to get right.
So Next!
Siemens as I probably should have done in the first place.
Well I followed the crowd and fitted the Siemens 850ccm (80ishlb) Injectors.
I'd be amazed if anyone can get a repeatable idle near 14.7 afr with batch fire and such short pulsewidths.
Heat soak makes a huge difference and life is too short to bugger about that much. Not that it really matters on a 36 year old car.
Thankfully my AFRs are still pretty close across the map, a little lean in places and a little rich in others, not beyond a bit of auto tune.
I now have loads of spare duty cycle!
My KLR is still functional, it literally gives me a knock signal and thats about it. I had been using it as a digital input, but it turns out the signal varies in voltage. So I've changed to an analogue input which seems to work nicely with the Microsquirt set to pull timing over 50% signal , I'm still not sure what the KLR considers bad knock. I only really get any knock at all off boost, except one event of WOT below 3k rpm @ 0.5 bar.
Being as I have two knock sensors on the block, I've wired the 2nd one to a line in on the stereo, Ive not driven it anywhere yet to test but the ignition (i assume) events come through very clearly. Its quite surprising I thought it would sound like a bag of spanners, I guess only certain frequencies are picked up, testing will tell.
I'd be amazed if anyone can get a repeatable idle near 14.7 afr with batch fire and such short pulsewidths.
Heat soak makes a huge difference and life is too short to bugger about that much. Not that it really matters on a 36 year old car.
Thankfully my AFRs are still pretty close across the map, a little lean in places and a little rich in others, not beyond a bit of auto tune.
I now have loads of spare duty cycle!
My KLR is still functional, it literally gives me a knock signal and thats about it. I had been using it as a digital input, but it turns out the signal varies in voltage. So I've changed to an analogue input which seems to work nicely with the Microsquirt set to pull timing over 50% signal , I'm still not sure what the KLR considers bad knock. I only really get any knock at all off boost, except one event of WOT below 3k rpm @ 0.5 bar.
Being as I have two knock sensors on the block, I've wired the 2nd one to a line in on the stereo, Ive not driven it anywhere yet to test but the ignition (i assume) events come through very clearly. Its quite surprising I thought it would sound like a bag of spanners, I guess only certain frequencies are picked up, testing will tell.
Had a tinker today, the car is now running very well.
It's difficult to get it tuned spot on due to traffic and safety, still a bit rich at low revs under boost.
Really needs a rolling road or I'm going to lose my driving licence.
Still not heard any of the knock the klr has picked up, usually at around 3k rpm, medium load, off boost. Maybe mechanical noise triggers it or its the same frequency as my tinnitus.
It's difficult to get it tuned spot on due to traffic and safety, still a bit rich at low revs under boost.
Really needs a rolling road or I'm going to lose my driving licence.
Still not heard any of the knock the klr has picked up, usually at around 3k rpm, medium load, off boost. Maybe mechanical noise triggers it or its the same frequency as my tinnitus.
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