Cylinder 8 running cold
Discussion
Finally had a bit of time and some better weather yesterday and managed to get the car out for a run.
The car idled well up to temperature and the AFRs pretty good on both sides. However the engine died the minute I blipped the throttle. From the logs, it seems that the idle valve was closing in too far, when dropping back to idle. I’d previously tuned the closed loop idle to use the initial value table, which was closing the idle valve too far, causing the engine to stall, before the idle control kicked in. I changed the setting to ‘use last value’ which solved the issue (ill have to retune the initial value table later).
I guess this proves that its been running with the injector vacuum leak issue for a while, at least since I tuned the closed loop idle earlier in the year but more likely since I refitted the injectors about 18 months (2k miles) ago. Not sure if this would have caused any damage to the engine, I’m hoping that this is only an issue at idle, and once at load with the throttle open, the cylinders will have been more closely balanced. I'm still planning to do a compression test, but the kit I ordered wont hold the pressure, so now waiting for a replacement.
On a positive note, on the short drive I managed, the car drove well and the tune wasn’t out by much, other than a bit too rich just of idle and on overrun. Amazing sound from the new manifolds, although possibly a bit too loud!
The car idled well up to temperature and the AFRs pretty good on both sides. However the engine died the minute I blipped the throttle. From the logs, it seems that the idle valve was closing in too far, when dropping back to idle. I’d previously tuned the closed loop idle to use the initial value table, which was closing the idle valve too far, causing the engine to stall, before the idle control kicked in. I changed the setting to ‘use last value’ which solved the issue (ill have to retune the initial value table later).
I guess this proves that its been running with the injector vacuum leak issue for a while, at least since I tuned the closed loop idle earlier in the year but more likely since I refitted the injectors about 18 months (2k miles) ago. Not sure if this would have caused any damage to the engine, I’m hoping that this is only an issue at idle, and once at load with the throttle open, the cylinders will have been more closely balanced. I'm still planning to do a compression test, but the kit I ordered wont hold the pressure, so now waiting for a replacement.
On a positive note, on the short drive I managed, the car drove well and the tune wasn’t out by much, other than a bit too rich just of idle and on overrun. Amazing sound from the new manifolds, although possibly a bit too loud!
VerySideways said:
What are you running throughout?
I've got the ACT long primary manifolds, the sports cats, and the ACT cherry bomb system. It's not quiet :-)
Same, ACT manifolds and cherry bomb exhaust, without the CATs. Previously running standard decat manifolds and Clive F Y piece. I've got the ACT long primary manifolds, the sports cats, and the ACT cherry bomb system. It's not quiet :-)
Edited by angus337 on Tuesday 27th October 15:12
3rd time lucky, but finally got a working compressor tester.
The 1st Sealey kit didn't hold pressure, and the replacement maxed out at 120psi, and then failed the same as the first. Got a slightly more expensive Draper kit and this one worked fine. I've only tested the offside cylinders so far, on a partly warmed up engine, but results were good as follows:
C2 - 184 psi
C8 - 186 psi
C6 - 190 psi
C4 - 192 psi
The results are in the order I did the tests. it seems a bit odd that the pressure went up with each test, not sure if there's a reason for this, or if its just a coincidence. There was a bit of time between the tests, as its a bit fiddly to remove the plugs and fit the gauge on a hot engine and by the time I got to cylinder 6, it had cooled down quite a bit.
Anyway pretty happy that the results don't indicate any issues with C8, and will get on and tackle the other side later.
The 1st Sealey kit didn't hold pressure, and the replacement maxed out at 120psi, and then failed the same as the first. Got a slightly more expensive Draper kit and this one worked fine. I've only tested the offside cylinders so far, on a partly warmed up engine, but results were good as follows:
C2 - 184 psi
C8 - 186 psi
C6 - 190 psi
C4 - 192 psi
The results are in the order I did the tests. it seems a bit odd that the pressure went up with each test, not sure if there's a reason for this, or if its just a coincidence. There was a bit of time between the tests, as its a bit fiddly to remove the plugs and fit the gauge on a hot engine and by the time I got to cylinder 6, it had cooled down quite a bit.
Anyway pretty happy that the results don't indicate any issues with C8, and will get on and tackle the other side later.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff