[zz_denis]

After 2 hours of browsing through half of the 248 "timing" threads that came up after a search and not finding my problem i give up

Showed my car to a pro engine builder today and he is as confused as i am!
Car runs and idles fine, when i start it COLD, the timing light shows the timing at about 7-8 deg. As it warms up, the timing keeps advancing and by the time its fully warmed up, it sits at about 17 degrees (advance).
The question is, what would make the timing advance like that? My guess is that the ECU is compensating for something, but what?!?! It would make more sense for the timing to retard actually, since the RPM's are dropping as the engine warms up. All the marks on the cam gears, crank pulley and CPS are alligned properly. The only thing that might be worth mentioning is that the compression is SLIGHTLY higher, with about 0.1mm less in between the head and block. Pistons are the forged ROSS stock compression units. If anyone can answer why the timing keeps creeping up like that as the engine is warming up, i will be trully impressed! (lol)

Another question is about the dammage that can be caused by running at 17 deg at stock boost (for now). I know that advancing the timing increases the chances of detonation if the fuel is not up for the task. I also heard some mention of "piston dammage", not really sure what that means, but would the forged pistons be more resistant to any sort of "dammage" ?

Thanks a lot for reading.
Dennis

 

[Guest]

Timing belt tensioned properly? *Shrugs* That's all I can think of. Usually the computer is the last thing to go wrong... It's almost always sensors or something else giving the ECU a false reading. Double check your Cam Position Sensor (CPS)

-Dave

 

[etdean2]

Did you put the jumper in daignostic port before setting the timing? You have to do that. After youget that you should be able to set the TPS.

 

[zz_denis]

Timing belt is tensioned properly, i checked that a bunch of times. If it was one of the sensors malfunctioning, i think the computer would pick it up, throwing a code. CPS is also fine, i took the thing out/adjusted it so many times, its not even funny.

The diagnostic terminals were jumped checking the timing, it doesnt make a lot of difference anyway. With the ports jumped the timing usually goes up by 1-2 degrees. By TPS i assume you mean the CPS ?

There is one other thing that i should mention. I did the 5spd swap and i kept the orginal automatic ECU. Most people keep the auto ECU without any problems though, so i dont think thats the problem. I heard that there are some minor differences in fuel maps in auto and standart ECU's but again, i dont think thats the problem.

I also used a JDM engine for rebulding, and it came from an earlier Supra too. (mine's late 89 and the engine came from a 87-88). Most sensors im using on the engine are the JDM ones.
Im starting to lean towards the idea that the timing issue is because of the 89 auto ECU compatability with earlier engine/5spd. I double-tripple checked everything else and it looks fine.

If anyone has any input, i'd greatly appreciate it.
Dennis

 

[etdean2]

No. The TPS is the black cylinderacal thing on the side of the Throttle Body. From the front of the car it is right behind the ISV (idle speed valve). With the jumper in you can move it alittle and hear the idle change. You also need to balance the TPS and the CPS. Also check your fuel pressure. I had my pressure refrence connectted wrong and the pressure did not change when I pulled the hose off. The fuel pressure should change. If you have the line connect to the wrong port under the intake, the fuel pressure will be up arond 38 PSI with the refrence hose ON. But it should be around 28psi with the hose on if you set the base fuel presure to 34-38 psi with the hose off.
You have checked for any leaks on the intake and all hoses? How far does the idle come down when it is warmed up? It should be around 650.
Since you changed with JDM parts, I am not sure if this will help, but I think ECU are similar.

Edit: Just so no one gets any miss-information, read ONE post down... aight peace :run:

btw, you also got some good points in this post except for the TPS

 

[sammydafish]

No. The TPS is the black cylinderacal thing on the side of the Throttle Body. From the front of the car it is right behind the ISV (idle speed valve). With the jumper in you can move it alittle and hear the idle change. You also need to balance the TPS and the CPS. Also check your fuel pressure. I had my pressure refrence connectted wrong and the pressure did not change when I pulled the hose off. The fuel pressure should change. If you have the line connect to the wrong port under the intake, the fuel pressure will be up arond 38 PSI with the refrence hose ON. But it should be around 28psi with the hose on if you set the base fuel presure to 34-38 psi with the hose off.
You have checked for any leaks on the intake and all hoses? How far does the idle come down when it is warmed up? It should be around 650.
Since you changed with JDM parts, I am not sure if this will help, but I think ECU are similar.

most of this post is wrong... sorry

the TPS is set per the TSRM, you set it on the idle contacts and then make sure its off idle at a few thousands of movement, see the TSRM for details, there is no balancing of TPS and CPS.

When you start the car, the ECU retards the timming for an easier start and keeps it this way for a little while to help the car warm up and idle easier. As teh engine approches operating temperature it will advance the timming. If you're at 17 degrees timming with the engine at operating temperature and the diag connected and your idle is good then it's overadvanced. Note that if the diag conector isn't jumped properly then timming will be in the 12-15 degree range at idle. Make sure your jumping Te1 and E1 on the diag block. The MIL should blink when connected.

*NOTE*
Also note that if you're using a timming light with a dial on it, you need to rememebr that the 7M-GTE is waisted spark, so if you use the dial the timming is doubled on your light. The best way is just to leave it at zero and align the crank mark to 10 degrees. That way you know it's accurate.

 

[zz_denis]

etdean2, TPS is mostly used to adjust the idle as far as im concerned, CPS is used to adjust timing. My car idles perfectly at 650 RPM as i mentioned in an earlier post so didnt think you were refering to the TPS. When i start the car cold it idles at about 1500rpm and then it takes about a minute or so to come down to 650 rpm. (on the old engine it took a bit more to go down to 650, maybe 4-5 minutes, but it doesnt really bother me). There are no leaks except for a very small boost leak on an upper IC pipe, shouldnt affect the timing though.

sammydafish , timing IS at 17 deg with Te1 and E1 jumped and engine fully warmed up at 650 rpm. I know its overadvanced and it shouldnt be there, thats what im trying to understand - why? 17 deg is also as low as i can get it with the CPS adjusting, its roated all the way "up". Timing light reads 650-ish rpm at idle too, not the 1300 like it reads sometimes so 17 deg is the "accurate" reading.

Thanks again

 

[sammydafish]

sammydafish , timing IS at 17 deg with Te1 and E1 jumped and engine fully warmed up at 650 rpm. I know its overadvanced and it shouldnt be there, thats what im trying to understand - why? 17 deg is also as low as i can get it with the CPS adjusting, its roated all the way "up". Timing light reads 650-ish rpm at idle too, not the 1300 like it reads sometimes so 17 deg is the "accurate" reading.

Thanks again

if 17 is the lowest you can get it, then the CPS was not alighed properly when you installed it. set the engine to TDC, remove the CPS and line up the hole per the TSRM, then reinstall.

You may also want to double check cam timming as the exhaust cam drives the CPS, if it's off, both valve and cam timing are off.

 

[drjonez]

sammy is da man! everything he said is spot on....do it!

 

[etdean2]

Well, Ok. You never said the car was idleing correecttly. So thats kool. I figured if you have everything correct with the CPS and TPS then it is something else. The TPS and CPS will working in conjunction with each other thru the ECU. If you don't think so, move the TPS to Higher idle, then take the car out. Go WOT to about 60 MPH and hit the brakes and put it in neutral. The car will die. Now move the TPS back to idle around 700 RPM, do the same thing, the car will catch itself and stay idling.
Anyway, Good luck. No big deal.

 

[QWIKSTRIKE]

Why do you think tsrm says check timeing at operating temp only?

 

[zz_denis]

sammy, thanks a lot for the input.
The weird thing is that the CPS *IS* alligned properly, i checked it many, many times. So are the marks on cam gears and the crank pulley.
What im going to do tomorrow is take the CPS out and actually allign it IMproperly. With all the marks at zero the CPS should be one tooth to the right of the mark (thats how it is now), and im going to make it two teeth to the right and then try to get the timing to be 10-12 deg that way.

What are the possible problems with running at 17deg at stock boost and 94 octance with forged pistons? I've heard of some of some Supras on race fuel running as much as 25 deg advance, and the Wilsonsupra guy said he was running at 50 deg on his 11 sec run.

Thanks

 

[chevyeater-on-sf]

Can't believe no one has mentioned that, if the TPS is misadjusted, the ECU will not drop back to base timing when you jump the Te1 and E1. Make sure the check engine light is blinking steady when you jump the terminals with the car idling, that is how you know it has dropped to base timing.

 

[ladmo]

If you are aligning the CPS correctly and your not able to get correct timing on that then there is prob something wrong with ur CPS. Try putting another one in there and see if that fixes it.

 

[sammydafish]

sammy, thanks a lot for the input.
The weird thing is that the CPS *IS* alligned properly, i checked it many, many times. So are the marks on cam gears and the crank pulley.
What im going to do tomorrow is take the CPS out and actually allign it IMproperly. With all the marks at zero the CPS should be one tooth to the right of the mark (thats how it is now), and im going to make it two teeth to the right and then try to get the timing to be 10-12 deg that way.

What are the possible problems with running at 17deg at stock boost and 94 octance with forged pistons? I've heard of some of some Supras on race fuel running as much as 25 deg advance, and the Wilsonsupra guy said he was running at 50 deg on his 11 sec run.

Thanks

If that's the case, then your cam timming is off. Check your timming belt, I'll be willing to bet that your exhaust cam is a tooth off.

 

[ladmo]

If that's the case, then your cam timming is off. Check your timming belt, I'll be willing to bet that your exhaust cam is a tooth off.

Another advantage to having your cam cover off

 

[zz_denis]

Chevyeater,
the light is actually not blinking steadly, it throws a code 51 (AC, which i dont have).

ladmo,
i have a spare CPS somewhere in the basement that im gonna try tomorrow.

sammy,
Cam timing is fine also, if it was something as simple as a misalligned cam or loose timing belt i wouldnt even post this thread in the first place, i checked that multiple times.

Im real pissed right now.. I went and talked to a master tech at the local Toyota dealer and he's got no idea whats causing it either.. other than the things that were suggested in this thread. What im probably going to do is just run some higher octane (98-100) and hope it doesnt ping at 17 degrees.

 

[Racefiend]

sounds like your cps is 180 degrees out. It's the exact symptoms you describe. Just because the holes line up doesn't necessarily mean it's right. Mine lined up correctly using the holes but was sitting 180 off. I assume someone rebuilt it and installed the drive gear 180 off, and thats why the holes lined up wrong. That or some line worker at the Toyota factory smoked a bowl the day he assembled my CPS.

 

[sammydafish]

Chevyeater,
the light is actually not blinking steadly, it throws a code 51 (AC, which i dont have).

ladmo,
i have a spare CPS somewhere in the basement that im gonna try tomorrow.

sammy,
Cam timing is fine also, if it was something as simple as a misalligned cam or loose timing belt i wouldnt even post this thread in the first place, i checked that multiple times.

Im real pissed right now.. I went and talked to a master tech at the local Toyota dealer and he's got no idea whats causing it either.. other than the things that were suggested in this thread. What im probably going to do is just run some higher octane (98-100) and hope it doesnt ping at 17 degrees.

code 51 means no idle signal, so listen to chevyeater, the ECU doesn't think you're at idle so it won't go to base timming. either your TPS is bad or it needs to be adjusted. it's easy to check with a DVOM. Make sure you're hitting the idle contancts --> http://www.cygnusx1.net/supra/library/TSRM/fi/FI_101.html

fix that and everything will work, problem solved

 

[zz_denis]

Checked the TPS with a DVOM and it was bad! Couldnt get a reading at either 0.5mm or 0.9 mm when chcking IDL-E2 terminals! I replaced the TPS with a spare one i had, adjusted it per TSRM and the timing is now fine! It's at 10 deg with CPS approx. in the middle. Sometimes the timing mark wobbles around a little bit (under timing light), from 9deg to maybe 11 deg, but i think its normal.

I cant describe how thankful i am to people who helped me in this thread! Especially chevyeater and sammy. If i see you guys on E-town meet, the beer is on me!

Thanks again!

P.S. racefiend, im not sure what you mean by CPS being 180deg out. Doesnt matter though, timing problem is now gone so i dont think there is anything wrong with my CPS.