Toyota Celica Supra Forum banner
1 - 15 of 15 Posts

·
Registered
1987 Toyota Cressida, W58 swapped
Joined
·
8 Posts
Discussion Starter · #1 ·
I recently tore down my 5MGE to replace the timing belt, pulley, and cam tower gaskets. I'm 99% sure my cam timing is spot on (TDC compression perfectly aligns the matchmarks on the cam gears and timing cover), and belt tension is even and within spec. However, whenever I insert the distributor (making sure the matchmarks on the gear and housing match up) as per the TSRM, it's always one tooth off, to the point where I can't adjust the distributor to 10* before TDC and still be able to insert the distributor adjustment bolt. I've been using a timing light and jumping the T and E terminals in the diagnostics port to adjust timing.

If I take it out rotate it as little as possible and try to reinsert it, the minimum distance I have to rotate it (to get it to insert) places it one tooth off on the other side of the 0-15 marks on the lower timing cover. On one occasion, before I had to take the upper timing components off again to redo the sealant on my exhaust side cam tower gasket, I got it to the point where 10* BTDC was right in the middle of the bolt flange, where I figure it's supposed to be, but I haven't been able to do that again since reassembling and redoing the cam gears and timing belt.

Before I redid the timing, the car's RPM fluctuated at idle and ran rich, which thankfully it no longer seems to do, but I suspect the previous owner might have had ignition timing issues too.

I'm not sure if this is related, but the car also seems to idle high, even after warming up, when I have the distributor timing at 10* BTDC and am no longer jumping the diagnostic ports. Not incredibly high, just more like a constant 950rpm (which can flutter between 900 and 1000) despite the A/C being off (and disconnected entirely). Doesn't need to be addressed if it's not relevant to distributor timing, just thought I'd throw that in there.

I've taken my distributor out, adjusted it, put it back in, and started the car to find it still one tooth off and not able to be adjusted to within spec (to be able to put the bolt in) at least 20 times now. Am I missing something obvious? Could both of my cam gears be one tooth off? What more can be done?
 

·
Super Moderator
Joined
·
8,754 Posts
Are you sure you're using the right mark on the shaft? It's the little divot not the big pin that holds the gear on. You should try and get the idle correct. The timing should advance with RPM. The whole point of jumpering the connector is to fix the idle position. Sounds like you might have a vacuum leak past the throttle plate.
 

·
Registered
1987 Toyota Cressida, W58 swapped
Joined
·
8 Posts
Discussion Starter · #4 ·
The reluctor doesn't seem to be adjustable at all. The cap is definitely stock, It even still has the wire connector protector/dust shield thing. I've opened it up to make sure none of the terminals are melted or corroded, and it all seems fine.

I have been lining it up with the little mark rather than the larger pin. I'll investigate the vacuum lines past the throttle plate. I sure hope it's not the line running parallel to the fuel rail, because that one really sucks to mess with without taking the upper intake chamber off.

If I understand correctly, the high idle may be advancing the timing, leading to my distributor gear seeming half a tooth off, so in theory if I get the idle down to where it should be, my problem may go away.

Should I be trying to get the idle right while the connectors are jumped, or should I disconnect that and try starting it normally (albeit with somewhat "off" timing)?
 

·
Registered
Joined
·
196 Posts
Turn the crank so that you're at 10°, then put the distributor in per the manual. When I had the crank at 0°, I had the same issues you did.
 

·
Registered
1987 Toyota Cressida, W58 swapped
Joined
·
8 Posts
Discussion Starter · #6 ·
Turn the crank so that you're at 10°, then put the distributor in per the manual. When I had the crank at 0°, I had the same issues you did.
If that's the solution, I'm gonna have to buy a hat just to eat it. Definitely trying that once it warms up later today.
 

·
Premium Member
Joined
·
6,238 Posts
16244
16245
Text White Black-and-white Font Parallel
Text White Style Line Black-and-white

Have you tried these timing methods, yet?
 

·
Registered
1987 Toyota Cressida, W58 swapped
Joined
·
8 Posts
Discussion Starter · #8 ·
Have you tried these timing methods, yet?
Yes, my timing still seems to be in order. I've redone the cam timing twice now (the second time was because I had to take the belt off again to apply gasket sealant to a still-leaking can tower gasket), and at TDC compression, the matchmarks on the cam gears align, and belt tension is uniform. The matchmark on the camshaft visible through the oil filler cap is also aligned. I did the timing in accordance with the TSRM.
 

·
Premium Member
Joined
·
6,238 Posts
You have checked EVERYTHING! What else is left. ?
Need more help here, guys.
Did the crankshaft key way let go?
 

·
Registered
Joined
·
196 Posts
If that's the solution, I'm gonna have to buy a hat just to eat it. Definitely trying that once it warms up later today.
I had to buy a hat to cover my bald head after pulling all my hair out over a seemingly simple issue, so I'm there with you. Surprised I didn't screw up the O-ring on the distributor pulling it and out so many times trying to get the right tooth. Fired up first time after turning the crank to 10 degrees and dropping the dizzy into the middle of its range. Happily idled at 650rpm or so after that.
 

·
Registered
1987 Toyota Cressida, W58 swapped
Joined
·
8 Posts
Discussion Starter · #11 ·
Before I continue, I have some possibly dumb questions to ask: how can I be sure that the T and E1 diagnostic terminals are jumped and the ignition timing can be set? I can't seem to discern any difference in behavior with the terminals jumped vs. not jumped. I opened up the back of the diagnostic port to check the continuity between the terminals to make sure they are indeed jumped. I got the car up to operating temp, accessories off, but with the ignition ON (engine not started), the CEL still won't flash like it's supposed to. I've only gotten it to flash properly once, and that was before I took the engine apart.

Do the same conditions need to be met as for reading trouble codes in order to set ignition timing, or do the T and E1 terminals just need to be jumped? Have I just been trying fruitlessly to set timing without the car truly being in diagnostic mode? Could my TPS be bad?

Also of note, when keeping the distributor timing at 10 degrees (without a bolt holding it in), the car was still idling high and it was running rich (the exhaust started pinging every few seconds) regardless of whether ignition timing was advanced or retarded. Maybe the ECU temperature sensor is bad?
 

·
Premium Member
Joined
·
6,238 Posts
My bypass has NEVER worked when I wanted to set my timing. I will never get codes. I need to see my DASH to see those codes. Never have. My '84 always runs rich=normal.
Set your timing as you see fit! My '85 engine likes 14* btdc. ok IN WINTER DRIVING...not IN SUMMERTIME.
tIMING IS A SMALL ISSUE. Caps lock, shit.
My '85 5MGE was all fucked up when I got the rebuild. Cams were NOT set correctly at the get-go.
Trust the cam timing? NO.
Set it like you have it and go. If you have to, CHANGE the dizzy hold down location.
Anyone else have an idea?
This is a weird puzzle, guys.
 

·
Registered
1987 Toyota Cressida, W58 swapped
Joined
·
8 Posts
Discussion Starter · #13 · (Edited)
SOLVED: I had the throttle position sensor set wrong!

After all this time, I finally figured it out. The throttle position sensor was installed such that it wasn't registering the throttle plate as ever being fully closed. Thus, I couldn't enter diagnostic mode, the idle was higher than it should be, and distributor timing was never right.

Confirmed this by jumping the bottom two pins of the TPS connector and finally getting trouble codes in the dash, the only one being "TPS error" because I shorted the pins, lol. I took out and readjusted the TPS with it still plugged in until it would enter diagnostic mode with the throttle plate closed, and lo and behold, it entered diagnostic mode, the idle was lower and smoother, the car sounded better, and wasn't running so rich anymore (no more pinging in my precious catalytic converter!) Now it happily stays at 10* btdc.

I am still getting a bit of a cosmetic issue where, after warming up, there's a bit of vibration in the engine. Not a lot, but not as smooth as a straight-six should be. What's strange is that sometimes it will go away for 5 seconds or so if I rev it just right and then let it go back to idle. Could be spark plug, vacuum leak, or fuel injector related is my guess.

Is there a good/well-known place to check the vacuum for leaks past the throttle body? Could it just be old gas in my probably near-empty tank (gauge doesn't usually work, so who knows), or a fuel pump issue? I'm all ears if anyone has any advice. I think I can hear a vacuum leak, but spraying carb cleaner around wasn't enlightening, and I couldn't affect it by pinching any hoses. I ran out of carb cleaner though, so I might have to give it a go with another can.

And another thing, I tested my ISCV and found that the TSRM's diagnostic test (testing resistance between S1 and B1/B3 and S2 between B2/B4) gave me the opposite results of what they should be. I only ever got 22 ohms between S1 and B2/B4 or S2 and B1/B3, when it should be the other way around. I've seen that a couple of times on here, but I haven't found anything confirming this to be a problem. It could just be the TSRM got things backwards. The ISCV does click as it should when the car turns off, but someone should let me know if the mixed up resistances are any reason for concern. For now, I'm just gonna ignore it.

Anyway, hopefully this dang thing will behave and decide to not leak oil onto the exhaust manifold just long enough to finally get it smogged successfully now that it's idling right at long last. Progress!

EDIT: pulled spark plug #1 right before heading to bed and boy is that thing fouled up with carbon. I thought my timing light was going out, then I tested it on plug wire #5 and things were working fine, so I pulled plug 1 to take a look. That would definitely explain the roughness after warming up.It would be awesome if that was the only issue.

EDIT 2: I cleaned spark plug 1 as best as I could and put it back in, and the car ran noticeably slightly better. The timing light seems to indicate that plugs 4 and 5 are firing less than 100% of the time as well (though much better than 1, which was firing a handful of times per minute), so I might as well just clean or replace all of them. I'm guessing some old fuel injectors are to blame, which sucks because those are expensive and require a pretty thorough teardown of the intake side to replace. Hopefully some seafoam or other injector cleaner will help so it doesn't come to that. Anyone have any recommendations?
 

·
Registered
Joined
·
7,465 Posts
Unfortunately I did not get it in your 2 post up that you had issue having the codes to come up. That is generally related to the TPS alignment, OR the little arm spring in it not free enough to come back to 'rest'. Had that issue with mine, and needed contact cleaner with lub sprayed fron the inside (TB side) so that little arm would come back enough to trigger the IDL input.
Glad you found the issue!
 
1 - 15 of 15 Posts
Top