Tsunami

Sorry for another one of these hard starting/rough idle questions, I did search and read through about 10 pages but im new at Rx7s so im still seeking answers.

Situation: got a 87 t2 off a friend CHEAP, jspec motor, s5 coil packs, pretty much a bastardized engine bay, friend lost interest in the project.
Problem: Takes a very long time to start and backfires, once it gets running I have to hold it at like 5k for about 10 seconds, then itll settle and idle.

From searching I guess possible problems are :timing, tps, plug wire crossed/need replaces, injector wires crossed, afm, am I forgetting anything?

questions:1. Ive never done timing before, could someone explain the function of a timing light to me, i tried my best to grasp its function from reading about timing but no such luck.

q2. I can play with the CAS back and forth to adjust timing if the car idles at roughly 750rpm, i adjust it to where it 'sounds' it should be, then retard it a few degrees, is this correct?

q3. Could someone link me to the 'proper' way to adjust tps (dont answer this if you dont want to, im still searching)

Anything else im forgetting or any other possible causes? Im new at Rx7s which makes it hard and I got the car with these problems, and cleaning up someone else's mess makes it 2x as hard. Thanks in advance.

RRTEC

iTrader: (13)

Forget all that and do this, check the thermosensor on the back of the coolant neck, make sure it is hooked up and the connections are clean and good....I bet this ul fix it man....it's a green connector, plug it up and enjoy. I bet he forgot to plug it up when the motor went back in...

trevor

Tsunami

thanks for the quick reply, could this connection being non-existant/dirty cause an overheating situation as well? I figured id ask questions on the above problem and tackle the overheating issue myself, but could be related? thanks again

RRTEC

iTrader: (13)

Overheating...no-.....The thermosensor tells the ecu how much fuel to dump into the chambers when "cold" starting..ie,,, not at running temp. that it why it is backfiring and you have to warm it up or it will stall on you...check the t-stat and see if it is working right about the overheating prob....DO NOT LET THE CAR OVERHEAT...It will blow the seals i promise you that... did you check the sensor yet?

Rotory

iTrader: (1)

damn rrtec u got to it way before i could...me and you are on a mission to make sure nobody else has to deal with this ****.

apexhittinbull

iTrader: (21)

sounds like bad water seal to me

Rotory

iTrader: (1)

what makes you think that...it doesnt sound like it to me and i have experienced a bad coolant seal first hand

RRTEC

iTrader: (13)

Coolant seals is an option too, if the car is smoking white constantly and having really hard starts AFTER you drive it at normal running temps- shut it off and try to start it like 2 minutes later. Say a ride to the gas station.ect. The coolant will seep past the coolant seals and collect in the chamber, thus creating a "hard start". It sounds like fuel related to me, water doesn't usually cause overcombustion (backfiring) becasue it is not flamable, Actually I know of a some people that run water injection systems in turbo modeled cars to keep detonation down. So You can almost rule out leaky water seals as a reason for your hard starts...
As for a timing light- this is one of my favorite things to do, Take the leads ( + and - ) put them on the battery. Then take the "clamp" and put it on either of the Leading or trailing wires. Then start the car and point the "gun" at the "pin" above the crank pulley you will emediately see 2 "flashing" white marks on the crank pulley, turn the CAS (dizzy look a like thing) untill the white mark lines up with the pin. Also a sure fire way to get the timing almost perfect on the first try is to, remove the CAS, manually turn the crank pulley untill the yellow mark on it lines up with the pin. Then take the CAS and line the "teeth" up on the bottom, you do this by lining the arrow on the back with a "DIMPLE" on the gear itself, carefully put it back in and it should be really close to perfect in time. hook the light back up and see where you are.
Here's a link to a TPS adjustment page
https://www.rx7club.com/showthread.p...adjustment+101

good luck.

trevor

Tsunami

so about this thermosensor you speak of, on top of the coolant neck by the alternator? If so there is definately a sensorish object there with an open male connector not plugged to anything. So assuming this is it, can this and the wiring/clip be picked up at an autoparts store? or is the wiring something i would have to source from a parts car? Also where does the other end plug into? Im hoping this is the problem, thanks for replies

Tsunami

so about this thermosensor you speak of, on top of the coolant neck by the alternator? If so there is definately a sensorish object there with an open male connector not plugged to anything. So assuming this is it, can this and the wiring/clip be picked up at an autoparts store? or is the wiring something i would have to source from a parts car? Also where does the other end plug into? Im hoping this is the problem, thanks for replies

Tsunami

so about this thermosensor you speak of, on top of the coolant neck by the alternator? If so there is definately a sensorish object there with an open male connector not plugged to anything. So assuming this is it, can this and the wiring/clip be picked up at an autoparts store? or is the wiring something i would have to source from a parts car? Also where does the other end plug into? Im hoping this is the problem, thanks for replies

RRTEC

iTrader: (13)

The female end should be somewhere near the alt in the wiring harness. It is also a green connector look aroung the wiring harness, If you can't find it, you'll have to buy a new harness from a junk yard, or figure out how to rewire it. Good luck that IS your starting probelm.....

Rotory

iTrader: (1)

yay...man u keep getting it before i do! The connector looks exactly like the BAC connector. if you cant find the plug i can sell u my spare plug cheap..maybe $10. I wish i had figured all this out WAAAAAAAY before the beginning of spring though...i had a whole winter full of push starting in freezing weather.

Tsunami

yeah i looked and couldnt find the clip. There was only one clip that I could find that would even reach the sensor and it was under the intercooler on the opposite side and definately wasnt green, in fact the only green ones I could find were 1 near the MAFS and 2 next to the battery. Maybe if someone could take me a picture and direct me where the harness/wires are coming from id have a better chance, but it would certainly be strange for it to be nowhere, and I looked for a solid 20-30 minutes, and there were no signs of the harness being cut, your thoughts?

Rotory

iTrader: (1)

look at your BAC connector....it looks exactly like that! the harness for the water thermosensor goes back towards the driver's side of the car under the throttle body