maz87t2

iTrader: (6)

i have a 88 se with turbo 2 engine and drive train all stock besides a front mount.it has 110psi in both rotors. the car will start with starting fluid no problem and run perfect after that. no issues. and it will fire back up after being hot. just the initial start up it wont start. it will flood after a bit.you go out a couple hours later and it will fire right up. you think it might be my injectors? im just tired of using starting fluid on it to get it started the first time. if you have any input let me know. im trying to get it running perfect so i can sell the money pit.

J-Rat

iTrader: (2)

Starter interlock for the AFM? That would be my first guess. Jumper fuel pump test connector and try to start.

maz87t2

iTrader: (6)

where is the fuel pump test connector? i have the fuel pump hard wired. i changed air flow meters and still wouldnt start on its own.

satch

iTrader: (1)

It's located by the passenger fender near the strut mount. It comes from the same harness that leads to the boost/pressure sensor. It comes encased in a rubber boot.

TrboSpdAnt

iTrader: (5)

+1 on the FP.

I would check the pump kicking on, when the key's at the 'pre-start' position... It's a pretty easy thing to diagnose: get to your fuel-pump access panel. Place your ear on the top of the plate and have someone else put the key to the 'pre-start' position.

You'll hear it humm and feel a mild vibration.

That'll last a couple of seconds, then kick off.

If you DON'T feel this check the relay for voltage and Ohms, per the FSM.

maz87t2

iTrader: (6)

the fuel pump is hardwired to the fuse box. its always running. the car will flood after a 30 seconds. it will be at 180 degrees and it will fire back up perfectly.

arghx

iTrader: (3)

check/replace the water thermosensor (2 wire sensor on back of waterpump housing)

maz87t2

iTrader: (6)

i replaced that and no luck. hailers can u chime in? im at a loss of what to do. im tired of having to start it with starting fluid. after i start it, it runs perfect. no problems and fires right back up after running for a few minutes. what would be causing this? done it ever since i put a new engine and ecu in it. this only happens when its cold. hellllllllpppppp

BadAssRX-7

well ive seen this with diesels...crack starting them the 1st time of the day or after cooling down. it is due to bad compression.
now on yours it sounds like a lack of fuel in some way.... fuel lines hooked up backwards? got the infectors wired up primes as 2nds and viceversa?

HAILERS2

Usually your problem which you describe as not starting cold but starting good once hot..........is related to the water thermo sensor on the back of the water pump housing (as was already mentioned).

The reason for this would be the ECU not seeing a signal from the water thermo sensor. IF that happens the ECU Defaults to seeing a 180* temperature. That's not good if the car is cold. Because the ECU has a internal START FUEL MAP that is used......for starting the car. It looks for the START signal from the key being switched to Start........looks to see what the water temperature is so it can select the right amount of fuel from the internal ECU start map........and looks for rpm to be under 500 rpms.

So if the signal from the water thermo sensor is missing and the ECU defaults to 180*.....then the internal fuel map of the ECU will select an amount of fuel that is too small to start the engine and the sucker won't start on a cold day. If you lived in Hawaii it might start easier.

So, anyway, once you start the engine with starter fluid and get the thing up to normal temperature, the car will start each time now because the actual/real temperature of the engine is comperable to the 180* default temperature of the ECU and that fuel amount is correct for a fully warmed up engine.

But you changed the water thermo sensor on the back of the water pump. Right? Didn't change the water temperature switch below the oil filter instead???

So I assume you changed the one on the water pump housing. My guess then is that the signal from it is not getting back to the ECU. That is usually caused by the two pin plug AT the water thermo sensor being the problem. You might pull that plug off and look in the elect plug to determine if one of the two contacts inside that plug is not making contact (like pushed back and not locked into the plug).

If that is not the case..........then on a series four car I would pull the middle ECU plug off and find the wire that is green with a white stripe. On the top row if memory serves. Then put the plug back on the ECU and back probe that green/white wire with digital volt meter (Harbor Freight....five bucks or so) and with the key ON engine OFF see what the voltage reading is. Should be about a half volt (.5vdc) give or take a smidge with a hot engine or if the engine is cold you will read??? something on the order of 2 to 3vdc. If it reads that then the signal is probably good. But IF the reading is 4.5 to 5vdc the connection b/t the water thermo sensor and ECU is open. That may seem odd to you but if you read close to 5vdc your reading just the internal device in the ECU. IF the wiring was intact the water thermo sensor would be pulling that 5vdc down to the earlier readings I mentioned.

OR your problem might be the ECU is not seeing the START signal I mentioned earlier. IF the start circuit to the starter has been messed with for some reason or the other, then someone might have eliminated this Start signal to the ECU inadvertently.

IF the ECU does not see the START signal.........it won't use the START FUEL MAP internal to the ECU. But instead it''lll use the AFM signal for the fuel amount during Start. NOT a good thing with a cold engine. The amount of fuel won't be sufficient.

As an side.............on a car that has HOT start problems, the lack of a START signal will prevent flooding during hot starts. The only down side to the ECU not seeing the Start signal is what your experiencing......difficult COLD starts (not enough fuel using the afm for fuel).

Note: after the engine gets over 500 rpm the ECU then uses the afm for fuel delivery and the START FUEL MAP is out of the loop.

I don't think I could fix your problem without knowing what the voltage is on the green/white wire and without knowing if the ECU is seeing the START signal when the key is HELD to Start.

The START signal is seen on the ECU's small plug and the water thermo sensor signal is seen on the the middle ECU plug. Water thermo wire is on the top row of that middle plug (2I is the one I think). START signal on the small plug is..........shucks I forget. It's a Black wire with Blue stripe and only sees voltage if the key is HELD to Start. Might pull that small plug off and look at that wire with a meter. Batt voltge shows up only if the key is HELD to Start.

Rambled too much on this thread. Your problem is one of those two things......lack of water thermo sensor signal..........or lack of the START signal to the small ECU plug. WAter thermos signal HAS to be read with the plug attached to the ECU. The START signal does not require the small ECU plug to be connected to the ECU.

Flooding is another issue and your not looking for that fix is the way I read this thread. That can be fixed some other day after the cold start has been fixed.

arghx

iTrader: (3)

yay hailers is back!

midnightbluefc

iTrader: (19)

amen.

spikespencer

Are you sure it is flooding sometimes and that this is a fuel problem? What do the spark plugs look like when you take them out? I ask since I recently had a long ordeal with mine not starting due to the starter not spinning up fast enough. I would of course go with Hailers' troubleshooting but it might be worth the $7 to wire in the starter relay if you think your starter might not be going quite fast enough.

~Spike~

maz87t2

iTrader: (6)

yes hailers i replaced the water thermo sensor from my last engine that would start up perfect when cold but not when hot since it only had 60psi of compression. put it in and didnt help. i used the same wiring harness that came off my engine that blew up. the only thing i changed was the ecu. traded my rtek 1.7 for a stock turbo 2 ecu and some cash. i wanted the car back to stock. i will get the volts later this week. i had a voltmeter but one of the wires broke. i want to buy a new n/a harness mine is pretty hacked up so that might be causing some of this. but it all started with the new engine. i will keep you guys updated.

maz87t2

iTrader: (6)

the green and white wire is .37 volts with key on engine off and the engine is cold. the black and blue wire is 1.75volts with the key on engine off and 1.27volts while cranking. would missing a ground from the chassis to the engine be the cause of all this? i forgot to put it back on when i installed the new engine. let me know what u think.

HAILERS2

Nah. There's something wrong here altogether.

A cold engine would read something like a full 2 to 3 volts with a cold engine. With a fully warmed up engine it'd read approx .5 volts dc. You'd do that with all the plugs connected to the ECU and be backprobing the green/white wire with say a paper clip or piece of thin wire shoved up its backside and the meter lead touching the piece of wire.

The ground for that sensor returns into pin 2C on a series four car. That would be the middle ECU plug and the second wire on the top row if counting from the left to the right when looking into the wire side of that plug.

The BLACK/BLUE wire on the small ECU plug seems wrong also. Key ON engine OFF it should read near zero. That would be done with the small plug off the ECU and key to ON ( no voltage) and then hold the key to Start and the reading should be about 9-12vdc if the starter is turning over as the key is HELD to start.

NO, both readings are wrong. I don't know what to say other than it's wrong. The ECU is not seeing the START signal when the key is HELD to START so that would explain a bad cold start condition.

The green/white wire has to be read with the key ON and all plugs connected to the ECU. Like I say cold engine should result in a voltage of approx 2-3 vdc (can't give you an exact figure 'cause I'd have to know the actual water temp) and approx .5vdc for sure if the engine is fully warmed up.

Personally I'd be looking at the lack of a start signal on the blue/black wire when the key is HELD to START. I think that is the real problem.

If somebody monkeyfucked with the starting system in the past, then that might be the reason there is no START signal at the ECU pin 3B (small ECU plug.....lower row.....last one on the bottom right if looking at the plug from the wire side of the plug).

I mean if somebody installed there own start button/switch, then I could see now they might have bypassed the signal to the ECU when the key is held to Start. The signal does not come directly from the ignition swithch, it comes from a wire further downstream and closer to the starters start wire (small wire on the starter solenoid).

Turbo in a non turbo car and switching some turbo harness into the non turbo car could cause this.

Put the key to ON. Then with the small plug off see if your meter reads approx batt voltgae on the two wires on the left end of the small ECU plug. Should. Both the B/W wire and the White/Blue wire should read approx batt voltage with key On engine OFF. IF they do, then that would reassure me the meter is reading ok and the gnd for the meter is indeed a gnd poiint (ECU bracket makes a good ground poiint).

So imho it's a lack of the START signal that is the cold starting problem. Starts good once fully hot tells me that. Lack of a START signal means the internal START FUEL MAP is not in play when you try to start the engine and the afm is being used for fuel delivery amount......which in turn will be not enough fuel for a cold start.

I used to post a chart showing this in the past. It might be found doing a search and using the terms HAILERS and CHART and finding the thread that shows that chart with explanation of how the start sequence is done on a RX.

HAILERS2

I should have said GRAPH for the search instead of Chart. The two jpgs in the other post are the same thing but one might be easier to read.

https://www.rx7club.com/showthread.p...ighlight=graph

On the second page of the thread is a picture of a PALM device showing he pulse width of the start signal CONNECTED in the first jpg and DISCONNECTED in the second jpg.

With the 3B connected to the ECU and seeing the start signal.................the injectors pulse width is open 17 ms.

Withe the 3B disconnected and the ECU not seeing the STart signal............the injectors pulse only about 5 ms. NOT enough fuel for a COLD engine but it would be just fine for a engine that is fully warmed up. Usually anything over 120*F would be warm enough.

The images I attached here don't wanna get bigger when I touched them but the same images on the thread I attached will cause the images to get large enough to read.

maz87t2

iTrader: (6)

it all looks original. how would i go about fixing this no start signal? i think im going to buy a new n/a wiring harness. the one i have now is hacked up.

HAILERS2

Well you could splice a new wire to the small trigger wire on the starter solenoid and then splice the other end to the BLACK/BLUE wire in the small ECU plug.

That same signal goes to a wire at the Circuit Opening Relay FYI so it could be spliced from there.

Which makes one wonder if the Circuit Opening Relay is also missing this start signal. If it is missing there, then the fuel pump will not turn on til the afm's vane has been moved aftwards at least a eight inch. After the engine starts with your starting fluid ......which makes the vane move aft..........the movement aft of the vane will put a ground on one of the two coils inside the Circuit Opening Relay and cause it to pull in and turn the pump on.

You can check this out fairly easy. Lay on the gnd and pull the trigger wire off the starter solenoid. Then HOLD the key to START. The fuel pump on a series four should run continuously with the key HELD to START. If it does.......then you know the circuit opening relay is pulling in when you go to start. Hmmm come to think of it, it probably is since you have no problems after the engine gets fully heated up. You might disregard this test/checkout.

Take note: that signal for the START signal travels thru the FRONT harness and not the EM harness on the engine........to the ECU small plug where the black/blue wire is. Pretty sure of that.

You might just get a piece of 18 to 22ga elect wire and just for grins attach that new wire to the trigger wire somehow and then stuff the other end of that new wire in the backside of the Blue/Black wire of the ECU's small plug and have a go at starting the engine. I'm saying just lay it across the floor of the car or anyway you want to do this test. Don't have to route it with the front harness. It would jsut take a small roll of elect wire bought from Pepboys or ???? wherever. even route it under the car and into the passenger side for a quick checkout to see if this help.

That said, I KNOW the ECU NEEDS to see this start signal when the key is HELD to START. Do NOT run a wire from the ignition switch..........but you could I suppose. You'd splice into the electrical plug there that has the black/red wire. NEVER splice into the wires right at the switch itself.

HAILERS2

I just lied to you by mistake. The start signal does go thru the EM harness for a short distance.

The signal is in the FRONT harness that runs across from the drivers side to the passengers side. That's the large harness that runs from one side to the other just above and in front of where your feet rest. Once on the passengers side it mates with the EM harness in a orange colored plug and now enters the EM harness and runs for a short distance to the small ECU plug (black/blue wire).

This orange colored plug has 13 wires in it and is not to be confused with the other orange plug that has a different number of wires in it. Anyway if one could follow the black/blue wire in the EM harness back from the ECU to the mating plug that is orange, he would fine that black/blue mates with a black/white wire in the mating plug on the front harness.

HAILERS2

BEWARE.......if you just find a wire with batt voltage on it and stuff it into the back of the black/blue wire at the small plug of the ECU.........that voltage will travel back to the starter solenoid and might make the starter turn over.

satch

iTrader: (1)

Perhaps a continuity test or two is in order like from the connector where the B/W wire carrying the start signal splits in two on its way to the starter solenoid as it veers off to the orange connector located near the ECU. Also, from pin 3B back to the orange connector (ECU side of connector), and then from pin 3B all the way back to the intermediate connector where the B/W wire splits, focusing on the single wire side of the connector.

And checking the voltage values at the pins one more time using the ECU mounting bolts as a ground for the meter reader if this ground point was not used in the initial test.

maz87t2

iTrader: (6)

good idea satch. i really appreciate all your guys help. ill go from there and keep you guys posted. usually i can figure everything out but these electrical problems suck.

HAILERS2

Here is a quick and simple way to prove your missing the START signal at the ECU.

Pull the ECU small plug off.

Get a piece of electrical wire which is bare at each end.

Stuff one end of that wire into the elect plugs socket where the Black/Blue wire is. That should be on the lower row of wires and at the far right end of the plug if looking into the wire side of that plug.

CAR OUT OF GEAR.

NO KEY REQUIRED IN THE IGNITION.

Touch the other bare end of your piece of electrical wire into the far left side of that plug where there is a WHITE/BLUE wire (constant batt voltage 24/7).

When you touch your bare wire to that white/blue wires contact, the starter will turn over proving that there is a signal each time you go to start the car with the ignition switch to start.

IF the starter does not spin................either the BTN fuse in the engine bay is bad OR the ROOM fuse in the interior is bad.........OR the circuit to the starters trigger wire is not getting to the ECU's pin 3B.

I just did this very thing on my old 86 RX and the starter spins up with no problems doing so. No injury to the wiring or anyother thing bad.

IF the blue/white does not work, turn the key to just ON and then use the BW wire directly below the white/blue wire in the plug. The black/white only gets power if the key is put to ON or better.

This is a trouble free and FAST way of proving the start signal is NOT getting to the ECU. Takes a max of thirty minutes to do on the outside.

The small ECU plug is NOT connected to the ECU when doing this. Your jumpering at the plug, NOT at the ECU itself. Just in case. Although I doubt it matters a bit whether or not the plug is in the ECU. Just easier to hold the plug in your HAND to do the jumpering than plugged into the ECU.

In fact I'm wondering if one could just jumper a wire b/t the white/blue and the blue/black and then go start the engine. You sort of bypass the START signal from the inngiton this way. I DOUBT it would hurt squat to do so. This is another way to prove the lack of signal to 3B is or is not the problem. I'd try this LAST after doing the jumper job I suggested just above.

HAILERS2

I've a little/big problem with this forum and the lack of knowledge of what and how the fuel delivery works upon start up. If one KNOWS whats what and had flooding problems, instead of making a fuel cut switch which could result in problems...............someone could just buy a voltage switch circuit from JAYCAR for thirty bucks and install it using the water thermo sensor as the trigger to open the start signal to the ECU once the water temp got up to operating temperatures. So the start signal would be there on cold starts but not there when warm or hot starts were being made.........and walla, no flooding and hands free operation. As in starting like a normal car instead of flipping a switch to off/on when starting the car.