Exhaust Camshaft Timing Toyota 3SFE

Ask for and share advice on using the PicoScope kit to fix vehicles here.
Post Reply
seafordmotors
OneWave
OneWave
Posts: 14
Joined: Mon May 08, 2017 1:26 am

Exhaust Camshaft Timing Toyota 3SFE

Post by seafordmotors »

Attached is the in cylinder pressure wave form of a Toyota engine at idle. I believe that the exhaust cam shaft is too far advanced. On this engine only the inlet cam shaft is driven by the timing belt. The exhaust cam shaft is driven through a gear of the inlet cam shaft. the marking to fit the exhaust camshaft is difficult to identify so a timing error can happen. This is a non interference type so there would be no piston/valve contact i case of incorrect cam timing. The distributor is driven of the inlet cam shaft. There is no Crankshaft position sensor so the exhaust cam shaft is not monitored. I do not have a reference wave form to compare the cam timing. Hopefully someone can help
Attachments
Toyota_Celica_1998_In Cylinder Pressure Idle.psdata
(3.15 MiB) Downloaded 51 times

seafordmotors
OneWave
OneWave
Posts: 14
Joined: Mon May 08, 2017 1:26 am

Re: Exhaust Camshaft Timing Toyota 3SFE

Post by seafordmotors »

I want to add that the car is a Celica ST162R and there are no camshaft phasers and has solid lifters.

User avatar
Fat Freddy
TwoWaves
TwoWaves
Posts: 335
Joined: Fri May 04, 2012 4:52 am

Re: Exhaust Camshaft Timing Toyota 3SFE

Post by Fat Freddy »

Off of memory. One of the gears are (possibly) a scissor gear, a 10mm bolt has to be inserted to lock the gear. On some of the other Toyota's there were two sets of marks, first to do the timing, the second to confirm.
I'd pull the rocker cover off and recheck the cam gears, the 3SFE is quite a simple set up (when you're used to them) and marking are usually quite obvious. HTH.

tintoverano
OneWave
OneWave
Posts: 34
Joined: Mon Dec 14, 2020 3:38 pm

Re: Exhaust Camshaft Timing Toyota 3SFE

Post by tintoverano »

perhaps try cam.crank correlation

it looks that ignition is late - I have no experience with this engine though

seafordmotors
OneWave
OneWave
Posts: 14
Joined: Mon May 08, 2017 1:26 am

Re: Exhaust Camshaft Timing Toyota 3SFE

Post by seafordmotors »

Thanks for the replies. I was after a wave form to show the cam timing if possible. This vehicle is from another workshop and I looked for an unrelated issue. ( Ignition system ) It actually runs not to bad . I wanted to know whether my assessment is correct because I have no reference wave form. So if anyone would have a in cylinder pressure waveform . As I mentioned this engine does not have a crankshaft position sensor. so you can not have a correlation signal.

ronw38
TwoWaves
TwoWaves
Posts: 65
Joined: Sun Aug 27, 2017 8:00 am

Re: Exhaust Camshaft Timing Toyota 3SFE

Post by ronw38 »

Hi Seaford
I think your first comment is correct, the pressure waveform I think, indicates an advanced exhaust cam.
Cheers Ron W

ronw38
TwoWaves
TwoWaves
Posts: 65
Joined: Sun Aug 27, 2017 8:00 am

Re: Exhaust Camshaft Timing Toyota 3SFE

Post by ronw38 »

Maybe I am thinking to hard, 1996 3sfe switched from distributor ignition with the crank TDC and Cam sensor mounted on the dist shaft; to a distributor less system with the crank sensor fitted at the crank pulley and Cam at the cam. As mentioned earlier the ignition timing looks retarded, if the ex cam is advanced and the dist has been adjusted to line the firing with timing mark on the crank pulley it would appear OK but the pressure pulse does not agree. I assume there has been disasembly of the motor? and what is the problem you are working to fix. Cheers Ron W

ronw38
TwoWaves
TwoWaves
Posts: 65
Joined: Sun Aug 27, 2017 8:00 am

Re: Exhaust Camshaft Timing Toyota 3SFE

Post by ronw38 »

I must stop thinking I should have mentioned this is a MAP controled engine and if the previous is the case engine vacuum will be down causing rich running! Ron W

seafordmotors
OneWave
OneWave
Posts: 14
Joined: Mon May 08, 2017 1:26 am

Re: Exhaust Camshaft Timing Toyota 3SFE

Post by seafordmotors »

This engine has a distributor with a engine speed sensor and a cam position sensor fitted as well as the ignition coil fitted. No map sensor but a vane type air volume sensor.Also no Crankshaft position sensor. Maybe there are different set ups in different countries. This is Australia

ronw38
TwoWaves
TwoWaves
Posts: 65
Joined: Sun Aug 27, 2017 8:00 am

Re: Exhaust Camshaft Timing Toyota 3SFE

Post by ronw38 »

I was not thinking with my comments on the distributor, its just a simple electronic unit superceding the old contact points system. Most of the 3fse systems I have seen use MAP but with so many changes over all the years of production anything is possible. If not already done check the manifold vacuum; low vacuum may point to a timing problem. Hope to hear of the fix. Cheers Ron W

Post Reply