Idle timing at +40 degrees!, WTF? and its not pinging!

[BenA31]

I've recently imported a 89 ceffy with a rb20det (previously a auto non turbo it appears). Have had timing belt changed along with a major service so far since its arrival.

Upon checking timing i aswel as the workshop have discovered that the idle timing is sitting at +30 degrees when the CAS is centered at where it normally should be at 15 degree. CAM belt has been double checked and is all aligned correctly and when put at top dead centre (i think thats what u call it) the harmonic balance also reads 15degrees where is should be.

even if we retard the timing the whole way it will not get to 15degrees.

so to double check that the timing was returning to normal upon load and acceleration we put it on the dyno, timing adjusted to normal as it accelerated/reved, no pinging was detected, power figure was at what it would be expected (116rwkw for completly stock car) , and was also running fairly rich.....

btw we have checked ecu and it is stock and not chipped from visual inspection. and was also tested with 2 different timing lights to varify that one wasn't broken.

does anyone have any ideas why its sitting at +30degrees at idle but as the revs increase returns to how it should be with no pinging or detonation what so ever???

i'm looking at swapping the ecu's with another rb20det soon, but other then ecu i'm kinda stumped and so is the workshop.

cheers

ben

[NZM.031]

so when you line the cams up on TDC the crank is reading 15 degrees.,.....are you serious??? if thats the case, you are waaaaaaaaaaaay out in your cam timing, when the crank is on TDC, so should the cams...

even with adj. cam gears, 1 tooth is 4 - 6 degrees.

to get the engine to run correctly, an absurd amount of ignition timing is required.

set the crank to TDC, it will have 5 marks in 5 degree increments, the TDC will be a different mark, it will be longer, or a different colour. then set the cams to TDC, and put the timing back to std.

i hope you havent done any damage to the engine.

cheers

Linton

[proengines]

It might be worth having a good look at your harmonic balancer and see if the outer ring has slipped/moved.

[Sydneykid]

I've recently imported a 89 ceffy with a rb20det (previously a auto non turbo it appears). Have had timing belt changed along with a major service so far since its arrival.  

Upon checking timing i aswel as the workshop have discovered that the idle timing is sitting at +40 degrees when the CAS is centered at where it normally should be at 15 degree. CAM belt has been double checked and is all aligned correctly and when put at top dead centre (i think thats what u call it) the harmonic balance also reads 15degrees where is should be.  

even if we retard the timing the whole way it will not get to 15degrees.  

so to double check that the timing was returning to normal upon load and acceleration we put it on the dyno, timing adjusted to normal as it accelerated/reved, no pinging was detected, power figure was at what it would be expected (116rwkw for completly stock car) , and was also running fairly rich.....

btw we have checked ecu and it is stock and not chipped from visual inspection. and was also tested with 2 different timing lights to varify that one wasn't broken.  

does anyone have any ideas why its sitting at +40degrees at idle but as the revs increase returns to how it should be with no pinging or detonation what so ever???

i'm looking at swapping the ecu's with another rb20det soon, but other then ecu i'm kinda stumped and so is the workshop.  

cheers

ben

Hi Ben, each mark on the crank pulley is 5 degrees.

[Topkart R33]

Make sure you unplug sensor off throttle body when checking timing.

[BenA31]

sorry my typo (too late at night when i posted this)... was actually 30 degrees not 40.

Cheers sydneykid, but yeah i know what each mark reads and it was deffinatly reading 30 degree's.

And topkart R33, yup that sensor was also dissconected. The guys at workshop took care of that while i was watchin. Plus set the idle at were it should be 650 from memory.

[BenA31]

so when you line the cams up on TDC the crank is reading 15 degrees.,.....are you serious??? if thats the case, you are waaaaaaaaaaaay out in your cam timing, when the crank is on TDC, so should the cams...

even with adj. cam gears, 1 tooth is 4 - 6 degrees.

to get the engine to run correctly, an absurd amount of ignition timing is required.

set the crank to TDC, it will have 5 marks in 5 degree increments, the TDC will be a different mark, it will be longer, or a different colour. then set the cams to TDC, and put the timing back to std.

i hope you havent done any damage to the engine.

cheers

Linton

cheers for the help. although all this was checked. and when the crank was on TDC the cams also were. all those little markings were lined up and all. that was the first thing the workshop checked and also showed me so i'd could also believe it with my own eyes. thats why its so wierd. seems as thou CPU or something is stuffing round with the timing while at idle but soon as the revs increase timing all returns to normal.......if the timing cam timing was as far out as expected i'm sure the car would have trouble even starting/running and sure as hell would not pull a stock power figure. i really gotta get my hands on another CPU when i get the chance......

[BenA31]

It might be worth having a good look at your harmonic balancer and see if the outer ring has slipped/moved.

yup valid point. i'll check this out.although doubtful, as the rubber on it looked fine under my quick observation last time i had a look

btw i've added the power curve for anyone to see. doesn't seem too odd to me.

also looking at the LAMBDA curve it seems like the air fuel ratio is healthy enough. running rich rather then lean.

[RB30-POWER]

Do you have the idle rpm correct when checking the timing, think its 15deg btdc @ 600rpm.

Also make sure the TPS is working correctly and registering that the motor is at idle/throttle closed, or else it may use an advanced timing value. (Bit like a limp mode)

[BenA31]

yeah idle is correct.

i'll give the TPS and ACC valve a clean out and see how it goes.

[Duncan]

I don't think anyone has mentioned yet....a lot of cheap timing lights read twice the timing on rb engine (no idea why). So your 30o may actually be 15o

[mabru]

I have a similar problem. Everything on my RB25 is set up correctly and the car runs ok but makes me nervous. The cams/crank line up perfectly and the CAS is centered which in the past has always been around 15btdc. My motor claims it's sitting at around 28 degrees or so at idle and doesn't ping at all. It feels like it needs a little more advance but I don't want to do it with it reading as high as it already is. I've tried various timing lights and one of them was a snap-on, all of them read the same.

The idle rpm is right, the tps is unplugged during the check, the engine is at normal temps, all marks line up, and I see 0 knock on the SAFC. I'm stumped, I can't find anything wrong with the engine or any of the sensors but that timing number has me concerned. My other RB never did this so this is a first for me. I'm glad someone else has a similar issue, I'd love to see the fix for this

edit: Oh, all my timing checks have been on a high tension lead off the number 1 plug and not that stupid timing loop (which is 14 degrees off on my engine)

[BenA31]

^ yup thats basically exactly what i have mabru but in a much better worded way, inc the method of checking the timing. and yup i'd have to agree with you. really makes me nervous to say the least even though everything else seems fine. for some reason i really think its the ECU, but gotta just find some spare time inbetween my exams to go swap ecu's with a mate of mine to see if there is a difference. but i also been thinking, could the knock sensor cause such problems if it is faulty?!? have you checked this on urs?, or better still, what so far have u checked and canceled out?

And duncan yup was checked with my timing light (cheaper one) first followed by the workshops better branded one which showed same results. So not sure on that one.

[mabru]

I have not, and I suspect that yes a bad knock sensor could cause this. My TPS seems fine, I've swapped the CAS so I'm pretty sure it's not to blame, I've checked almost every sensor and they all check fine. The only ones I've neglected to look at are the knock sensors, that would explain my loss of power, I'm not sure why the engine would think it's so far advanced when it isn't though.

[mabru]

Update:

I think I've nailed it. CAS nub was worn on the edges causing the timing to shift quite a bit. For the first couple minutes after starting the car it ran like a demon, then the ecu would pull the timing out and ran like garbage. Replaced the CAS and the idle changed, egt's changed, and fuel curve is out of whack now but the car still feels stronger. I need to retune.

I'm pretty damned happy

[Bl4cK32]

got any pics of the worn cas "nub"...so the rest of us can see it

[mabru]

got any pics of the worn cas "nub"...so the rest of us can see it

Haven't taken any yet, it's really hard to tell from visual inspection. It looks a little different than the one I put in. The edges were a bit rounded off. I suppose the entire unit could be bad. I'm just happy the thing is back to normal.

I can take a pic when I get home after work, I'm not sure how well pics will turn out though.

[jaik]

Dont forget an RB20DET Auto Motor/Loom/ECU will want to run 20degrees whereas the Manual engine/loom/ecu combo will want 15 degrees. Pretty sure it says that under my bonnet!

Im manual now but have an Auto Engine (as noted by the TPS etc) and I run 20 deg.

JK

[Cubes]

skypy12,

Forget the ECU, the ecu has no influence over the timing light read out.

The idea is you match the two, 15degree's at the crank and 15degree's base inside the ecu.

Also you stated,

CAM belt has been double checked and is all aligned correctly and when put at top dead centre (i think thats what u call it) the harmonic balance also reads 15degrees where is should be.

The harmonic balancer is set to 0degree's or TDC, and both cam gears are set to TDC or centerline 0degree's.

But as said, cheap timing lights do read incorrectly on some RB's.

On mine it does, the only one i've seen work is some fandangled digital one that you point and it displays the ignition timing.

[BenA31]

well i have since now swapped ECU's with a mate who has a manual R32 gtst.

and whola timing ran at 20 degrees. which is a 10 degrees drop from the 30 it was running with my computer. (which is what i want it running considering the car used to be an auto)

i have no idea. why or how this logically was causing the problems but meh now i'm looking for a manual r32 or Cefiro computer.....

BTW: nothing else was changed on the car between the ECU swaps....