testing tps without starting car
 

well it seems that no matter what i do i can't get my car to run. its really driving me nuts. i can get it to start if i do the oil in the lower plug holes. but everything in the car checks out as good, even the water thermo thing so dont even suggest telling me to test it. anyways since it is a bitch to get started and warm up i was wondering if there is another way to test the tps. and also will a faulty tps keep the car from starting? im not sure im out of ideas and since this is my dd i need it fixed asap.

Yes you can test it without starting the car. If you still have the fast idle/thermowax system, you will need to rotate the little arm upwards to disengage it.

But I doubt that's the reason why your engine doesn't even fire up. Is the engine flooding out? What's the history of the car? How old is the motor and when did it last run?

its got the tb mod so none of that would be an issue.

the engine is flooding out. not sure why but it floods insanely fast. first turn of the key. its a TURBO SWAPPED base s4. no emissions. the motor is fairly new, just got done breaking it in on a "fresh" rebuild. and it was running fine until one day i was gettin on the freeway and got on it. i hit a 6k roadblock and couldnt go passed it. ever since then its been like this. tried 3 different ecu's and not a single difference.

it seems to want to start with the tps unhooked. but still didnt take off... so anybody have ideas? or is this going to end up being another thread where rx7club doesnt want to help?

The TPS has ZERO to do with starting the engine.

And just for grins, the AFM has zero zippity to do with starting the engine.

And don't dare ask if the alternator has anything to do with starting, please.

Did I mention checking out the water thermo sensor at the ECU and seeing what voltage it reads when hot? When cold?

Sounds more like a blown engine/dropped apex seal. We assume the TID did not come off at the turbo nor the ducts that leave the turbo, ducts at the intercooler didn't fall off, small tubes on the intercooler did not fall off. Nope, blown apex seal it is.

^ +1

I agree a compression test is in order.

wierd cause with the tps unplugged it started right up.

also its got good compression. already checked that. thought it was an issue but nope. and also while deflooding it you can hear it and it doesnt sound like a bad apex seal.

when it cools down, its like 100 outside already, i will check the voltage of the waTER thermo sensor. anyone know right off hand what pin it is on the ecu?

and also the gasket between the turbo and downpipe is gone. not sure what happened to it but its gone. will this affect anything? like give the o2 sensor false reading? cause after i start it and let it warm up i hit the gas and seen all the extra oil i stuck it come out of here as smoke. and its a lot.

Pin 2I. With key to "on," .4volts to 1.8volts when warm and basically 2 to 3 volts cold.

well i went to test pin 2I and this is what i came up with
its roughly 95* outside, not sure if that affects it. but while cold it was about1.5vdc and once warmed up it was .4-.5vdc. so these numbers appear to be ok right?

also i might add that while attemping to start it would just crank and crank and crank. so i pulled olugs de-flooded it and added some oil and it started within half a second from me turning the key.like nothing

.4 to .5 volts warmed up is just right!

but what about the cold readings? my issue isnt anything to do with running. it seems to run like a top. im just having issues with starting it.

If the engine was started up prior to the testing and therefor warmed up the coolant then your cold start reading might not be fully accurate. Pehaps letting it sit overnight would be best before taking an accurate reading.

the engine WAS NOT started for about 24 hours prior to me testing the voltage "cold". which was 1.5vdc. now is that what it should be?

after i recorded that number i started it and let it warm up. this was the first time it ran in a 24 hour period.

Service manual says .4 to 1.8 volts when warm but with the warm temps you reported that would affect the cold start reading. How much? I do not know.

ah. well since my cold reading is in the same range the FSM says it should be for hot this will explain why it always wants to flood when starting. doesnt seem like that bad of an idea to replace it, its only about 15 bucks. so ill swap tht out and see what i get. also ill try again when its closed to 75-80* outside later tonight..

well new thermo sensor did nothing for me. everything is in good working order but the fucking car wont start still. i see why people put v8s in their car. at least on the v8 forums they can get help

satch i just want to confirm, where are you getting theese numbers, or is it just an expierience thing?
the FSM (F1-80) states pin 2I with the ign on it should read 4.5-5.5v and says nothing on wether the engine is warm or cold.

i searched and searched and couldnt find those number you speak of. but i believe that is prolly what i want to be seeing with the engine cold. not the 1.8vdc that i am. i think possibly i might have got the wires mixed up cause i had to swap out the old plug. can someone post a picture of their plug so i can see that i got mine hooked up the right way?

Below is for S4 NA. Turbo has the remark "Warm Engine."


http://img844.imageshack.us/img844/9...upinout.th.png

so can anyone answer me? is the 1.8vdc that im seeing while the engine is cold good or bad? should it be higher or lower?

You could disconnect the plug from the thermosensor and unscrew it and place the sensoring part in a cup of water that is 68 degrees and then measure its resistance as it should read (2.45). If the water in the cup were heated to 176 degrees then the resistance ought to read (.32). You can't get the water to -4 degrees but if it were possible the reading would then be (16.2). This comes right from the FSM. Nothing more, nothing less.

o S4, S5, turbo, N/A, im a moron!

the sensor is brand new. i dont see a need to measure the resistance. all i really wanna know is if my reading of 1.8vdc is what it should be cold. if not then i have to figure out why... ugh i really just want my car to be driving. nobody has any suggestions for gettin it to start? everything is checking out fine but it just wont start.

TPS have NOTHING AT ALL TO DO WITH AN ENGINE STARTING.

There is NO given value for the output of a cold water thermosensor BECAUSE what is COLD??? 80*F, 40*F, 77*F????????????

There is in the FSM a procedure for checking out the water thermo sensor by ohming it out at different water temperatures. See book. The resistance equates to what the voltge will be ....more or less. There's a little more trickery involved than I =E/R stuff.

That said, somewhere in the past I logged on this forum the vdc values of the waterthermo sensor at different water temperatures. I used my RTEK 2.0 with PALM to look at the water temperature and used a Fluke backprobing the 2I pin in the middle pulg. I made up a list of different temps vs voltage.

The FSM gives the temp for a fully warmed up engine BECAUSE they put a approx 180*F thermostat in the engine and know what a fully warmed up engine temp is so they can put down a voltage for that temperature which is ???? 0.4 to 0.5 vdc or whatever the FSM says it is.

The volt and a half your getting sounds reasonable to me given this is summer and all. Cold engine.

Get someone to pull the car around the block if you Know you have spark and fuel. That's a first time I ever suggested that on this site.

so your solution to my starting issue is just have someone pull me aroudn the block? that really doesnt help me any considering i can get it to start in teh drive way with oil in the plug holes. i wanna be able to hop in it and turn the key and be on my way. but i have no way of doing this because i have no idea why my car is dumping tons and tons and tons of fuel into the motor

...

Did you ever test the fuel pressure?

IF you really have spark and IF the timing is close to spot on and IF you want the ECU to deliver much less fuel during START.......depin pin 3B of the ECU (black/blue) wire in the small plug, bottom row, far right).

As noted in one of the threads I pasted earlier, if the ECU does not see the start signal on 3B, then the ECU does not use the internal start fuel map but instead uses the afm signal which will deliver I'd guess, about a third or less fuel in ms when the engine is trying to start. As an example instead of the injector staying open 20 ms it'll only stay open 9 ms or less during Start.

Pulling off the water thermosensors plug will do close to the same thing.......ECU defaults to 176*F which in turn means much less fuel delivered during START. Also means the engine Might run a bit too lean til the engine water temp gets up to the actual 176*F.

Or unplug the fuel pump and spray starter fluid into the intake snorkel for no more than three seconds then start the car. Repeat three or four times then reconnect the fuel pump. I did NOT say pull any EGI fuses. That is not the same thing as uplugging the fuel pump and spraying starter fluid for three seconds into the snorkel/air filter.

Unplugging 3B also works on HOT starting problems. The only down side is that when the weather turns cold as in below sixty degrees or less, then difficult starts happen again 'cause this time too little fuel is delivered.

i will try to depin pin 3B and see what that does for me.

and no i havent checked the fuel pressure. i dont happen to have a fuel pressure tester..

If your pressure is too high then it stands to reason that the injectors would emit too much fuel when they are in the open position. Not sure it works that way but I thought I would throw it out there for others to confirm or deny.

That makes sense. Did not occur to me. Fixated on it being something else. Harbour Freight sells stuff at unbeliveable low prices ( can we say low labour costs?). Might buy the cheapest fuel pressure tester they sell and tee it into the fuel pressure line right at the engine hard line (b/t the filter and hardline on the engine). Should read approx 37-39 psi with key ON, engine OFF (that part should be easy). Then maybe just attach the gauge into the output line from the filter with key ON...........pressue should be approx 80 psi (see FSM for exact figure range) for deadhead pressure from the pump with nothing else in line.

Or a sticking fuel injector. Not my favorite thought. I've never had one and never sent any injectors out to the cleaned. Have bought new injectors in the past but that's it for me and injectors. I doubt this is your probem. My predjudice.

ok so test it before and after the filter? will do. and as for injectors i doubt that is the issue. they were just serviced not too long ago.

After the filter and before the hard line and you'll need to tee in the gauge to get an accurate reading. Also, if your water faucet was working perfectly but you increased the water pressure to the house then the faucet would emit more water at say half open then when operating at a lower pressure. Make sense?

Sounds like a fuel issue to me, I had a problem with my 87 TII,I had bad primary injectors it would dump fuel over night to he point it would actually come out the Exhaust, try taking out the EGI fuse and crank it over a few times. Then put it back in and try firing it up.

Tee'd into the fuel line coming off the filter will give you the pressure that the FPR is regulating the fuel to. IF you just connect the gauge to the line coming off the filter and no tee is installed, you'lll read the full output of the fuel pump. YOur really just interested in doing the tee thing so you can see what the fuel rail pressure is.......or if you will, what the injectors see as pressure.

Fuel runs continouously thru the fuel system and back to the tank. The pressure in the rails is determined by the FPR which is the LAST thing in the fuel rails. It holds the pressure required and dumps the rest back into the tank and it cycles thru over and over and over and over and....

its beyond doing that. trust me.


ok i will do it with the tee. after looking it up online it looks like thats the only way to hook up the testers. so i will give tht a try and see what it says. but yes satch what you said makes perfect sense.

If you remove the plugs do you have fuel coming out?

yes. tons of it. i've already said that. and pulling the EGI fuse and turning it over does not help because as soon as i try to start it again it refloods.

ok so i just read up on your hot start thread and seen its exactly what you told me to do and it mentioned something about when it gets cold out that this will not work. and here it gets damn cold in the winter.. now wouldnt it be smart to wire in a switch rather than just ridding the harness of the wire? of course have that switch tucked away since it'll only be flipped once a year. this seems like a better solution to me. what do you think?

What exactly do you mean by your injectors were 'serviced'?

Did you put some snake oil into it that supposedly cleans them out? Because that's not good enough.


I had flooding problems with my old NA motor. I had them sent out to be flow tested + cleaned then the problem pretty much went away. That's the only real way to clean them out. Don't waste your time/money with snake oils.

oh wow. thank you a billion HAILERS!!!!!!!! it started right up when i cut that wire. but once warmed up i had a little issuew with getting it to actually start again. i had to hold the little flap in the AFM and "choke" it to get it to start. but its like a whole new car just by cuttin that wire. it even idles at 750 now rather than 1000 rpms

witchhunter thats what i mean by serviced. i wouldnt ever waste my money on tht junk in the stores,.

Depinning that wire should only effect STARTING and nothing else. The ECU has a START FUEL MAP and uses that internal fuel map during starting only and ignores the afm until the engine gets over 500 rpm. Fuel is determined by the afm for any other situation. Sorry you cut the wire instead of depinning it from the plug. Hope you left enough wire to resplice it in the future if needed.

If it idles better now............that's due to something other than depinning 3B.

The ECU only knows to use the internal start map when it sees the 12vdc signal on pin 3B, and that signal is only there if the key is HELD to START.

You might resplice the wire the next time the engine is hot and see if the problem still exists or not. Like with it respliced you could see if it'll start again or not without messing with the afm.

well i already explained my reason to cut it rather than depin it. but it was only that one time i had to hold the flap. it seems to fire up now. now that this bug is done and outta the way time to move to the next one....