SupraDremr

iTrader: (5)

Hello,

I recently changed my head gasket on my 1992 SC300 5 speed. I followed the service manual the whole way. Car ran fine and idled normal prior to doing the head gasket. However, When I started the car today for the first time It ran ok but had a intermittent put put sound that wasnt in time it was erratic...Like it would hiccup twice in a row then just run then hiccup once then fine then hiccup twice rpm needle jumping around...But it didnt sound like it was hiccuping in the same sequence it was eratic. When the car warmed up the stutter got more pronounced and the rpms would go from like 1000 to 400 then back up to 800 then down to almost 0 then back up to 1000 and so on...The needle just dances. I figured it was just a matter of fine tuning the timing adjustment by rotating the distributor... But rotating it to any point didnt seem to remedy the problem. Matter of fact it only stays running with the distributor clocked almost all the way counter clockwise or down towards the back.(Hope that makes sense) And before(before I took it apart to do the head gasket) the distributor was clocked almost all the way to the clockwise direction or to the top of the slide on the distributor. If I put it in the same position as before it doesnt want to run. No check engine light at all... My battery light is on though now which I have never had on before. Hoping that is just because the battery was sitting outside for a week while I worked on the head gasket. I have checked and rechecked my vaccuum lines with my manual and from what I can tell I have the lines routed properly. I have test driven the car and it seems to accelerate pretty normal, slight loss of power fro what I remember but nothing major. Another note. When I took the distributor out when disasembling the engine the timing adjustment nut was almost clocked to the highest point or clockwise point that you can roll or slide the distributor....Now it seems to only want to stay running with the distributor nut all the way down to almost the bottom point or counterclockwise position... There is also a smell of gas that is noticable when the windows are down or I am outside the car.


If I can describe this a better way or need to clarify anything or anything at all to help you guys in helping me, let me know. I have had my car out of service for over a month now and I really wanna get this figured out and start driving her again... Its got to be something simple or stupid...Well I hope so at least.

Thanks!!!

SupraDremr

iTrader: (5)

Nobody with any ideas??? I am out of ideas at what could be causing this. Been tinkering and rechecking everything I did when reinstalling everything and cant see where I went wrong... I changed the head gasket to a TT Supra OEM gasket... Before it had a fel pro oem for sc300's on it. I had a machine shop machine my cylinder head and he said it was warped and had to be milled 4 thousanths past factory specs.... But that I should be okay because of the thicker head gasket I was using... Not sure how this would cause an idle issue just trying to help you guys help me. I used arp head studs and replaced my timing and serpentine belts with gates racing belts...

What would be anyones guess???? Vacuum line mis route? Or an actual part malfunctioning? About ready to pull my hair out.... I just wanna go for a nice drive in my beautiful sc....And have it run like its supposed to again...Help Please!

soarer13oy

iTrader: (13)

i would assume its some sort of vacuum leak maybe from the intake manifold or timing is a bit off maybe?

TheAzn

iTrader: (2)

Are you re-using the timing belt components? If you are, chances are it slipped if you are re-using it. Tensioner is too weak, timing belt is damaged or both.

Check the spark. You can go to an auto part store and buy a SPARK TESTER, $5-$10. Basically it's a pen with a gas-filled tube in it that is sensitive to electricity. When the tip of it comes in contact with a wire, it lights. Use it to check for sparks in each wire, no need to disassemble anything. Basically hold the tip of the tester to each of the wires. If there's spark in ALL wires, given the fact that you are smelling gas, could be a mis-aligned timing belt. Sparks at the wrong time, like sparking during the exhaust stroke or something.

On my old Corolla before I pulled the motor, it ran fine. Then one day it started with a putt here and there which eventually got worse. Noticeable loss of power. The lower timing gear slid over a key to keep it in place. The key slot on the gear somehow wore out so the gear was able to move making the timing belt misalign by one or two teeth. Just enough to screw everything, chew out some other teeth, then performance problems.

Vacuum leaks - You can check by listening for any hissing sounds. You can use Carb Choke Cleaner, Brake Cleaner, Starter Fluid or anything like that in a aerosol spray can and flammable and spray the lines in different areas or areas where there are vacuum lines and you hear a hissing. If there's a vacuum leak, the spray vapors will get sucked in and you should notice a change in how the engine runs. Just be careful, it is flammable. But if there's no open sparks and whatever, you'll be fine, just don't spray it all over the place. Just a spit.

SupraDremr

iTrader: (5)

The azn- Yes i am re using the timing belt tensioner... I have double checked that my timing as far as being on top dead center or the 0 mark on the crank pulley and lined up perfect with my cam gears pointing to the top dead center marks on the top timing cover... For that reason, I dont believe the issue is belt slippage... The belt is brand new and is a Gates Racing Blue belt...I will double check the timing belt placement again today though and see if it has slipped any...All vacuum lines are plugged and there is no leaks, I will again for like the 4th time recheck the routing of the lines and see if I made a mistake there. Some of the diagrams in the manual are a little confusing when the lines cross each other in the picture. I will also go and get a spark tester and check that out to rule out a misfire issue...Thanks for the responses guys... I really wanna get this all figured out. I am also gonna try and get a timing light today to set the timing... Our distributors only slide in one of two ways: the right way or 180 off in which the car just cranks and wont start at all... (done it before). So it could be an issue of the fine tuning done by sliding the distributor on the pivot nut clockwise or counterclockwise... However, like mentioned before, the car only seems to want to run on the downside or counterclockwise position, when I clock the distributor clockwise it just dies...

beenlookin

Jesus, i'm having the exact same issue on mine. Just replaced the HG as well and now it stumbles like an ill tempered donkey at idle and at steady highway speeds but is perfect otherwise. No one can figure out the problem. It seems like an ignition issue but all the parts are new (plugs, wires, cap, rotor)

Have you had any luck in figuring it out? After all that work, this cant be happening!

SupraDremr

iTrader: (5)

No solution as of yet.... I have family I town and it has been hard to spend much time trying to figure it out. New plugs, wires, serpentine belt, timing belt... Arp head studs, Toyota oem tt supra headgasket.... I don't see what the problem could be... Should just run dangit! Think I am gonna have to throw it in a shop tomorrow for diagnostics and hope they can at least pin point the issue and then I will at least know what needs to be fixed.... But by you saying your having a similar problem and no one seems to know what the issue is kinda worries me.... I don't wanna spend 75-150 on diagnostic for them to say they don't know either... Anyone else with some input on what it might be?

spitfire7

My car was doing the same thing. Then it died, and didnt want to start. I just stopped driving it. I've been waiting for someone to find out what it is. If no word soon Im gonna put it in the shop.

SupraDremr

iTrader: (5)

I got a guy on a club on facebook that seems to think he knows what the problem is, says he is 98% sure what it is but the final 2% would be seeing and hearing the car and knowing for sure.... Only problem is he wants 85 bucks to come "diagnose" it and tell me for "sure"...Wish he would just tell me what he is 98% sure it is.Only thing I can guess from research based off of what he said in response to me and the questions he asked is it is timing related... The only thing I have read that I didnt do timing involved was set the timing with a timing light and the diagnostic port terminals jumped... Most of what I read says something about needing to jump the te1 and e1 in the diag port while adjusting the timing on the distributor... I read that in the service manual but I figured that was only if you were using a timing light....But it would make sense to have to do it even if you weren't using a light but still trying to fine tune it...Something about it not letting the timing advance during the adjustment I think. I am going to try to adjust the distributor tomorrow with the to spots jumped And try and get the engine timed properly and post the results...Can't bring myself to pay someone 85 bucks just yet for something he could just tell me in a message that he thinks it is...UGH

beenlookin

Although it sounds like your timing, it probably isn't. I took it back to my friends (both mechanics) who looked at the timing again and it's dead on. He even hooked up a Snapon Modis diagnostic tool, everything seems okay. Problem is the cars are so old they dont throw errors out for little things like this.

As far as mine is concerned, we replaced:
-OEM HG
-OEM HG Bolts

AND WHILE WE WERE IN THERE:
-water pump
-timing belt
-serp belt
-valve cover gaskets
-thermostat
-radiator hoses

All spark plugs/wires/cap/rotor replaced last year with all OEM equipment. ONE plug replaced a couple days ago in the cylinder where the coolant was entering with like OEM NGK model listed in the owners manual.

I cannot figure this out and my friends have all but given up and told me that it's just gonna be that way. Hate to spend any more money in a car that's two decades old but this misfire makes it immensely frustrating to drive. Amazing how smooth it is otherwise except when stopped with a load on it and cruising at highway speeds.

Supradrmr definitely let me know of your findings. GL

SupraDremr

iTrader: (5)

I think we are experiencing a little different issues then maybe. My car hesitates constantly, more noticable when warmed up....and intermitantly the idle will jump from 1000 to 400 then to 800 then almost 0 then 1000 eventually dying, sometimes in a few seconds or sometimes stays going for 5 mins or so, has a wierd muffled putt sound in that can be heard most noticably from the exhaust pipes. If I drive it, I can feel the hesitation at idle and it feels like there is a lack in power from what I am used too, no noticable misfires though while accelerating, seems to accelerate in uniform but muffled a bit. When I come to a light or stop sign the idle dives towards 0, sometimes recovering, sometimes it just dies. I pleaded with the guy that seems to think he knows what it is to just tell me but he said it would devalue the perception of his knowledges worth or something like that... Whatever that means....Can't justify 85 bucks to myself or my other half at the moment. I am gonna try and adjust the distributor with the diagnostic ports jumped and see if I can get the distributor clocked back up where it used to be when the car ran fine before I tore it down. If it changes nothing though I am gonna be at a total loss, once again lol.... Gotta get this figured out by the end of this weekend...

beenlookin

got it bro... either way let us all know whats up.

I saw these when browsing, not identical but thought i'd share:

https://www.clublexus.com/forums/per...ideas-pls.html

http://www.supraforums.com/forum/sho...nd-coil-wiring

SupraDremr

iTrader: (5)

Okay well it seems as if I solved the idle jumping and hesitation. What I did was I rotated my crankshaft to top dead center and made certain the cam gears were also lined up to the timing marks on the metal timing cover that is behind the cam gears... I pulled my distributor and put it back in making certain the rotor was facing the spot where the number one spark plug wire goes into the distributor cap... Upon starting it up it seemed to run a little smoother but was a little rough still...I hooked a paper clip in between terminals te1 and e1 on the diagnosis port in the engine bay, I borrowed my neighbors timing light and adjusted the timing to the 10 mark to the left of the top dead center mark on the crank pulley.... Car quieted down and seems to run just like it did before I started this job... I will let you guys know if anything else gores wrong or if it wasn't a true fix... I went for a few test drives and it seems to perform just fine though... What a relief!

TheAzn

iTrader: (2)

Could it have been possible the dist rotor was in the wrong position?

SupraDremr

iTrader: (5)

I guess its possible.... From what I understood the distibutor only goes in the right way or 180 degrees off....In which the car just cranks and wont start...But removing and reinstalling the distributor seemed to remedy the problem...The clocking of the distributor also changed when I reinstalled it... The car was able to start with the distributor clocked back where I remembered it being at .... I then adjusted the timing while having the correct terminals jumped in the diagnostic port and adjusted it at the 10 mark to the left of the 0 for top dead center.