drifter_xs

okay so today i tried to set timing on my car. i changed all plugs and wires. i set idle around 750rpm. i hooked up the timing light(clamp to T1) and i noticed that my timing was way off. the red notch was 2-3 inches to the left of the needle. i stabbed the CAS properly. so i turned the CAS counterclockwise all the way and it got closer to the red notch but not close enough. now it idles all weird and it even backfired afew times. what should i do? im stumped. anything i should look at or adjust or anything? any ideas what is going on?

87 rx7 NA
full tune up was performed

thanks guys

jdonnell

iTrader: (1)

Pulley 'Yellow' mark should align with pointer operating at idle; red align at higher rpm (I think 2000rpm). I had something similar where yellow lined up but after increasing rpm the red did not line up. I re-set it again and it worked fine. Also, did you ground the initial set coupler before you timed it.

hungery4rice

iTrader: (7)

Sometimes you can't go by the marks. I just had this same issue. Tried to use the timing marks on the pulley and it was having trouble idling. Best bet is to find top dead center and pull the timing about 5 degrees off.

RotaryEvolution

iTrader: (30)

and how do you propose finding TDC? i've thought of every method and none work reliably besides pulling the front hub off the engine and using a pre-marked hub/pulley combo. flywheel weight angle is about as close as you can get roughly, but still not very accurate. apex seal to apex seal through the plug holes is WAYYY off for TDC due to the plug holes not being concentric to the engine(last time i checked on a series 4 it came in at 35 degrees off of actual TDC). very minor changes in e-shaft angle result in dramatic timing offsets since the rotors only move at 1/3 crank speed.

the yellow mark is the one you need. yellow leading is at about 1:30 on the pulley and trailing red is at about 1 o'clock.

red trailing does not require anything special to check aside from moving the timing light lead to the trailing #1 plug wire. this simply checks to be sure the timing split is functioning and the ECU is in what i call 'idle mode'.


some improper FC hub to pulley combos during engine overhauls with mixed up parts resulted in 3-15 degrees off of actual TDC. luckily most found were retarded and simply resulted in power losses versus detonation related failures but it can go the other way, and with high horsepower applications can cost engine after engine.

drifter_xs

i did

RotaryEvolution

iTrader: (30)

the engine should be idling below 1k RPMs otherwise setting base timing is null.

if it's nowhere near then the CAS is probably stabbed improperly.

drifter_xs

now my car just starts up. backfires then dies. it would take some effort to crank over. now it doesnt wanna stay running.

drifter_xs

i mean it takes some effort for it to start

hungery4rice

iTrader: (7)

Start by removing the two plugs for the rear rotor. Use a small mirror to look into the spark plug holes and when you see the apex see in the trailing holes make a mark on the pulley. Continue turning the motor clockwise and when the apex seal is in the center of the leading hole, mark the pulley. Measure halfway between the two marks you made and that will be top dead center for the front rotor.

Did this a couple weeks ago and it worked. My pulley was about 60* or so off. Not sure how.

De-Mystifying

RotaryEvolution

iTrader: (30)

as i mentioned in the quoted post that method is about the furthest off from actual TDC. note how the plug holes are offcenter to the rotor in the housing and you will see why that method doesn't get you to a perfect TDC setting, it actually puts the engine extremely advanced to the point of possibly damaging the engine. this would also explain how the pulley was off so far, because i doubt it was. add in the mis-match pulley combo possibility and the timing marks could be 45+ degrees off by using that method.

if your pulley really is off time, the best recommendation i can give is to get an aftermarket solid hub/pulley to set the engine to TDC(the racing beat pulley for example was accurate, though i still noted it to be off by about 3 degrees but that is "close enough") or buy a new pair from mazda.

i have seen numerous cars come in with extremely advanced timing and the cars started and ran ok, with the slight hiccup/kickback during cranking but on turbo engines audible detonation was heard.

i read that article and decided to test the theory for myself and found the results to be far from spectacular and quite misleading. i even would suggest they remove it but it can serve a purpose. on 12A engines for example the hub can be mounted 90-180 degrees off since all the hub mount hole are equalateral and this method can find which of the 4 positions is correct without all the trial and error involved.

adjust the CAS to the point that the engine will run and idle somewhat smoothly below 1k RPM, jumper the initial set coupler and check timing again. off leading plug #1 the pointer should point to the yellow driver side mark, on trailing plug #1 wire the pointer should point to the red passenger side mark.

if that all checks out after timing the engine and it still has difficulty starting/running you may have a front hub mismatch which is throwing the timing off or another unrelated issue to timing that is causing the starting issue such as low fuel pressure/low engine compression/vacuum leaks. adjusting timing can supplement and mask other unrelated issues.

if the engine is fresh with low compression or very old and tired sometimes you simply have to compromise with the timing if you want to buy more time with it until it either breaks in or breaks.

hungery4rice

iTrader: (7)

Yeah I see what you're saying RR. My issue was I replaced my front cover gasket and when I put everything back together my timing was way off. I installed the CAS per the FSM almost 8 times to make sure I was doing it correctly. The car sounded like it wanted to back-fire and wouldn't hold an idle. I used the method I mentioned and backed it off and estimated 5* and it idled great. I'm not trying to say this way is perfect, but it gets you in the ballpark using a pulley with the timing marks off.

drifter_xs

So I got the car to idle first start in the morning.i warmed up the car I followed procedures and adjusted to spec. It held idle spot on and I shot timing (to first timing marker) and it's set. Buuuuuuuuut when I tried to rev it up it stubbles and backfire gunshots and dies. Any ideas?

drifter_xs

Problem found and fixed. Car is running great. It was a faulty wire to the fuel pump. It would get hot and resistance would occur therefore voltage would drop. My friend kelvin arreola of KA autoworks pointed it out. Then BAM. It ran nice.

P_Lav

Sounds like I problem I may be having, how did you trouble shoot?

satch

iTrader: (1)

I guess if you have a voltage wire powering the pump that if you measured the ohms/resistance of this wire and it increased w/time to an unacceptable level that it would be an obvious sign that something is up.

RotaryEvolution

iTrader: (30)

usually i just stab the black/white wire where it goes through the inspection plate under the rear carpet. measure the voltage cold and warm, and loaded when warm if possible.