W00dface

Im having trouble getting the car to fire up.

Fuel is getting through and it's firing a spark.

Im pretty sure cts is shot as it's giving a multimeter reading of 3.4 and the fans are firing up when I turn the key. ECU is not giving any codes either. Not even a 55.

Im compleatly stumped as to whats going on.

maxitech

iTrader: (7)

A new one is cheap and easy to install...Give it a try!

W00dface

Not in the UK they aren't. Nissan is after £90 ($135) !!!!!!!

Im going to order one from the states but it will take a good few weeks to arrive and need to get the car going ASAP so if it's not that, will be another 2 weeks without the car.

BenStoked

iTrader: (7)

it should be giving a 55, at the least.
give it another try.

W00dface

Nope. wont even go in to diagnosis mode. Just a red light.

It was firing up a week back (has sat since) but ran really really bad (dies after a few seconds of rought idle) ECU was the same then.

biggz2332

iTrader: (5)

Cause a car not to start I highly doubt it, the CTS main purpose is to get good performance when the car is cold.

W00dface

Im of the same opinon but it's the only thing that has changed (fans coming on when ignition turned to engine on)

Unless of course, something else is making the fans kick in and the car not start.

Would a fried ECU do this?

BenStoked

iTrader: (7)

does the tach move when you cranK? have you checked the ECU fuse?

W00dface

Nope no movement in the tach (other than the needle vibrating). Where is the ECU fuse located?

BenStoked

iTrader: (7)

under the dash, with the rest of 'em. I don't remember which one exactly, but I know it's a 10a (or should be), like 4th or 5th down. on the right side. the fuse is labeled eng. cont. or something.

W00dface

cheers. I'll go through all the fuses tomorrow as they are not labeled and it's dark over here now.

Taken the battery out to give it a good full charge too just incase.

biggz2332

iTrader: (5)

Yea do wat benstoked says and check for the ECU fuse first before you lose yourself, I think the only two sensors that would make a car not start is the cam and crank position sensors if I'm correct.

Matt93SE

iTrader: (44)

A CTS will cause the car not to start. this is actually fairly common. The ECU uses the engine temp as an indicator of several things, one is whether to go into cold-start (very rich) mode or not.

On OBD-I cars, the computer uses the MAF and the CTS to try to determine some sort of air density. When the CTS fails, the ECU assumes the engine/air temp is near absolute zero. since gasses contract the colder they get, the ECU basically assumes the air is very very dense and dumps a shload of fuel into the engine to compensate.

I found this out a few years ago when the CTS on my old Chevy truck died. the fuel injectors would just HOSE gas into the intake when the truck was cranking. Eventually the ECU threw an error code about the CTS and I read the manual to find the proper resistance values. the sensor was off, so for a truth-check I grabbed some resistors out of my electronics parts shelf and plugged them into the CTS wiring to simulate a cold start. truck fired right up!


Soooo....
First, try disconnecting the sensor and see if the ECU will give you blinky lights instead of just sitting there with a red light. (Think about this guys.. if the ECU fuse was blown, how would it be getting +12V to fire of the red LED?)
It's worth a shot to check the fuse, but I highly doubt that's your issue. If something else has failed to ground- like the CTS- then it's possible that it's dragging the ECU down with it. unplug the CTS and see what happens.

If that gets the ECU back into blinky mode, try and start the car without the CTS plugged in. If that doesn't work, grab a couple 470k and 1k resistors. string them together to make about a 2k load, then plug that into the CTS. (That simuilates a 20C engine temp)
See if it'll start..

If it starts, let it warm up and when it's hot to the touch (50C) stick a 1k resistor in it.

See how that does.

DoctorPete

You can disconnect the plug from the coolant temp sensor and with said multimeter do an ohms test for resistance IN the CTS. This means you have to be testing on the CTS (prongs) not the connector side of the circuit. With the engine cold resistance (ohms) should be high and when the engine is warm the resistance (ohms) should be low. You should be getting readings like: 10 ohms (very cold engine) to 0.15 ohm (hot engine). I have a feeling you will be getting low ohms since the fans are going on the sensor is probably reading hot. Good luck.

LvR

The use of Massey Ferguson farm impliment service procedures is not allowed for troubleshooting 3rd gens

Matt93SE

iTrader: (44)

For a Maxima,
fan on = high resistance. (i.e. unplug the connector and the fans come on)
fan off= low resistance

Dhunterx

iTrader: (6)

Not trying to thread jack, but where exactly is the CTS located? I'm wondering if it might have to do with my issue on troubled starting. Car runs smooth as butter, but sometimes has a hard time starting (not sure how to describe it, it feels like it has trouble catching, and it takes a longer time turning the key to get it to start).

richard_85zxt

since you have an 89 GXE you have a VG so it would be in the front side head behind the timing belt cover. Doesn't sound like your issue is cts though. the CTS is coolant temp sensor, which can when reading cold adjust your timing and make the car not start more or less because it tells your ECU to set the timing wrong. If yours runs great but just takes more cranks to start I'm gonna say it's not your CTS. I'd go with battery almost dead or starter. If it were distributor, plugs, wires, etc. it could cause a hard start but wouldn't run "smooth as butter" but that's just a general thought without asking more details since I don't think your situation relates to this thread. I'd start a new thread explaining your issues and any details to get proper help.

W00dface

The fueses are all ok. Disconnected but ECU stayed a solid red light.

I'll try and find some resistors. Depends on what I can pull apart as it's pretty imposible to get individual components like that without ordering off the net.

Im going to get the ecu out in a biut and just check everything is still connected as it should be.

Prior to this happening, the car would suddenly run bad then shut off and I would have to leave it awhile before I could start it up again which makes me think CTS was reading high then.

Dhunterx

iTrader: (6)

Battery and starter are new. I'm going to have to get a video going, cause I've replaced a lot of stuff to try and figure out how to get it to start up normally.

Darkwing48

iTrader: (1)

SWI (Sticky Worthy Info)

MikeJL

OK, the fellow that says you should try to add grounds first before changing anything is the best first remedy attempt for this problem. This is a long story but I think it is worth it.

In a nutshell, assuming the cause is not a sensor malfunction (or broken sensor wiring), the engine is behaving with at least two of these initial conditions:

1. Over the past few months or more, the engine cranking before start has lengthened. "It doesn't start like it used to"
2. The engine acts as though it is resisting the starter and actually stops the starter dead in it's tracks at times.
3. The engine runs great after it starts.
4. You recently changed out a tranny / clutch ie: you disassembled the bell housing from the engine.
5. your starter doesn't have the pep it used to.
6. The car is older (don't tell that to the car)

All or some of these conditions is caused by a weak or high resistance ground somewhere in the path between the starter and the battery. Contrary to what may seem intuitive, the electrons that flow in the battery circuit actually flow from the negative terminal to the positive terminal in a battery. The positive terminal is + Positive because it has fewer electrons than the - Negative terminal. When the circuit is completed (starter turns on) the circuit wants to go to equilibrium and the excess electrons flow to the positive terminal from the battery negative terminal.

OK so now how do these electrons get to the starter? Well in the infinite wisdom of trying to save money on car costs by manufacturers, the manufacturers decided many years ago to do away with the negative wires on cars (in many general cases like lights, horns, sensors and the like). This led to the idea for the car manufacturers to make the body of the car and engine, tranny etc) the negative cable from the battery. In essence the car itself acted as one big wire from the battery negative cable to the devices in the car. Connect a bulb to any + power wire in the car and the other terminal to any metal body part and the bulb will light. This confirms that there is a direct connection to the negative terminal of the battery.

As a car ages, the connections to the car body or engine or transmission degrade and become corroded. This corrosion impedes the flow of these powerful electrons from the battery to the device being operated (sensor, starter, light, horn, etc). Couple that to the inherent properties of corroded, poor conducting aluminum and you have the beginning of a slow but ever increasing problem.

Now the best part: The car runs fine but the engine has a problem only during starts and sometimes intermittent at that....This 'only during a start' tells you that the starter is involved in the problem - but it is not the cause. You see when the starter cranks it draws a relatively enormous amount of power (amps) through the ground of the starter through the motor of the starter through the positive battery cable. In most cases, the path of electrons is from the negative battery cable to a point on the engine block through the bell housing seam on the engine to the flange of the starter motor (bolts included). Just think, if I were to place an electrical insulator between the engine and the bellhousing joined to the engine would there be a negative path for the electrons to flow to the starter? No not at all (excluding bolts).

So, when your starter is acting sluggish or burns out (because it was designed to operate with a full clean connection to the negative terminal) it makes sense that the reason is a poor connection to the engine - the place where the connection to the negative battery - electron source is made via the engine block to negative battery terminal.

Phew! we are almost there hang in!

Now with a poor or highly resistive connection to ground (through the engine block to bell housing to starter motor flange), the starter "hogs" all of the available electrons to turn the starter motor over. So what about the sensors? What is left for them to tell the ECU when to fire or which cylinder to fire or which cylinder to inject, or when to inject, or when is Top Dead center? The answer: too little. It gets even worse in cold weather when the engine is stiff and the starter takes even more power to turn the engine over. Even more power is robbed and the sensors have even less to work with.

It's like trying to do 50# curls while running uphill...the curls and the speed of the run both slow down.

In an engine system, the sensors typically detect around 0-5 volts. But as the poor connection 'robs' the sensors of say 6 volts, it makes it much harder for the ECM to "see" the intended signals from the sensors resulting in wrong signals. This is the voltage loss in the starter circuit.

It is like two people taking a shower in a house from the same hot water tank. The fellow with the bigger pipe or closer to the tank (first floor) gets all the hot water while the other on the top floor freezes because his shower is too far away.

What happens when the first floor shower is shut off? Does the guy on the second floor get hot water? Of course he does. And just like our engines, the moment the car starts and the starter is shut off, all returns to normal and there are plenty of electrons / voltage for the sensors.

Have you noticed this problem often happens after a tranny or clutch job? What happened? Easy: the engine to bellhousing / tranny joint was not properly cleaned and reconnected to make a good electrical contact and chances are cleanliness was not even on your mind when you bolted everything back together! Tell me who cleans their hands under a tranny!

OK OK enough already I believe you got the picture. So how do we solve this?

I would do this in this order (do one at a time) and try each step to see if it works before going to the next:

1. Put a new negative battery cable in the car. If the battery cable is highly resistive due to green corroded crimped ends it may 'rob' the engine block of electrons needed to operate the sensors and the starter simultaneously. Put the cable in - in 2 sections: from the battery to the body ground then from the body ground to the engine block.
2. Run a ground to the larger bolt of the starter from the body ground in step 1.
3. Run a ground from the body ground above to the Bell housing bolt at about the 10 o'clock position looking at the rear of the engine. Stay away from the Crank POS sensor because of EMI (another long story not for now).
4. So now you have four wires under the bolt at the body ground - no problem - be neat and make sure they are all laid flat against one another.
5. Lastly, run a smaller wire - say 12 ga to the engine sensor / ECM ground on the air intake collector (FSM 118 and 119 grounding points) where there are 4 black wires under 2 screws - 2 each screw). This shouldn't be a problem but it is easy. Connect this right to the negative battery terminal bolt.

OK, so this should work if you have a grounding problem due to old age. In fact, what you just accomplished is a one, two, three or quadruple bypass surgery for grounds. In each case you "bypassed" the original ground path - but who is counting?

Of course the best way to solve the problem is to completely disassemble the engine, tranny, bellhousing, starter, alternator, etc etc, clean and reassemble - but com'on who does this?

Remember: Aluminum is a great conductor but only when new and bright clean! Aluminum oxide does not conduct and this is the root of the problem that we need to deal with.

I have run out of words....good luck!

PS use NO-OX-ID A Special conductive grease on your ground connections - good stuff - electrical supply places should have this.

--

Matt93SE

iTrader: (44)

You're run out of words? You used up the bandwidth for the entire internet to give us this useless post!! This is a mainetenance issue, not an oxidized ground issue. A bad ground will rarely, if ever, cause these cars not to start. There's enough chassis grounds on this engine to make it start, although it may be a bit sluggish if/when they get corroded.
Considering the car still cranks over well, then I highly doubt the grounds are an issue. there's a 4awg ground between the engine, chassis, and battery, and the ECU is grounded very near that.

Cliff Clavin

iTrader: (11)

Woodface -- My coolant temp sensor went bad a few years ago. The car ran awful, it had trouble starting and it acted like it was possessed by demons. I am not making this up.

It did, however, throw the proper ECU code for a bad CTS. It cost about $20 for one here and took maybe 5 minutes to replace.

If you have any difficulty getting one, let me know and I can buy one from NAPA for you and ship it. I am pretty sure it will fit in a small International Flat Rate box or Flat Rate envelope for $13. It says 6-10 days on the site, but the last time I sent an Int'l Flat Rate, it only took 4 days from Oregon (western US) to the UK.

Max_5gen

iTrader: (2)

I think, you've got it wrong - the opposite is true: the CTS resistance lowers when temperature increases. You stated this yourself a while ago: "~3kohms on a cold engine and about 300 ohms on a warm engine". So fan would come on when resistance is low. ECU program is not completely dumb though so when it detects that CTS is completely disconnected it turns the fans ON as well 'just in case'. This creates false impression that lower resistance would turn them OFF.

To OP: the fact that you can't get ECU to blink 55 is really suspicious in my opinion. Is there any way to substitute your ECU with a known good one or put yours into another car? You can also check CTS resistance using numbers published here before. If it's within specs I'd leave it alone.

W00dface

I have ordered a new cts via ebay USA a few days ago so hopefully will get that this week and be able to rule that out as a problem.

The ECU is when im becoming more of a suspect though as I can't see why it would just sit there with a single red light. I've not had the chance to remove it yet and check all the connections. Hopefully I will be able to do that this eve.

I can't test it with a working ECU as I just can't get one over here (apparently there are less than 10 3rd gens in the UK!!!)

shiloh51933

iTrader: (5)

I know my local yards i can pick up new used ECU for cheep and yours definately sounds suspect to say the least. The MAF has been known to give problems in the starting area but first I would check ECU for a code but yours is not working so you need another, good wrenching, Shiloh.

Max_5gen

iTrader: (2)

It all depends how accurate you followed the procedure to switch it to diagnostic mode. If you're absolutely sure you did this correctly then I have little hope CTS will help. Turning red led on doesn't require much from ECU as all it takes is one wire sinking some current. So, if say ECU is completely fried and its outputs are all shortened to the ground the red led will be also lit while ECU wouldn't react to anything as you understand. This situation is extremely unlikely, I'm just illustrating my point that turning led on doesn't take much 'brain'.

Can you check CTS resistance? In your case it should be close to 3kOhm as I don't see how you can get engine warm without starting . You should measure it directly on CTS prongs, after taking off its connector.

Cliff Clavin

iTrader: (11)

Does your car have a VE or VG engine? Manual or Auto trans?

I have an extra VE 5-speed ECU from my parts car I just removed.

InfinitiForever

I agree with the posts above, It should be giving a 55, just buy and install a new one its shouldnt be too difficult/pricy. Good Luck.

W00dface

CTS is reading 3.7k. After putting it in the freezer i got it down to 3K but it made no difference. I guess the CTS is knackered but not the main cause of the problem.

It's an SE with VG30 auto in (all we got in Europe)

In the UK they are really hard to get hold of.

Still not been able to get round to taking it out and checking connections etc. If not will order one next week.

What confuses me though is before this happened the car would run for 5 mins then totally die. I would have to leave it a few mins before being able to restart it (just didn't fire up). When it did re-start, it would die again a few mins later.

I then tried it a few days later after this happened and it would fire up but run really rough http://www.youtube.com/user/w00dface.../0/j22u4UkXyoE I could hear a vacuum leak near the rear injectors so ended up pulling them. I found two of the o-rings really badly split so replaced them.

Now it wont start at all.

Max_5gen

iTrader: (2)

Beats me how you managed that - CTS resistance is supposed to increase when temperature drops. You should make sure multimeter ends don't touch anything except prongs when making the measurement. Your hands, for example, conduct electricity and can skew the result. 3.7 kOhm is good enough, it doesn't have to be exactly 3kOhm.

As I said, if you're sure you followed 'switching to diagnostic mode' procedure correctly replacing ECU seems the best bet. I'd still check its connector of course and open it up to see some obvious problem before ordering the replacement, just in case.

W00dface

Im just that good

I have ordered a new CTS now. Pretty sure it's knackered.

Anyways, got my ECU out and opened it up. Part of it is burnt out. Looks like water has got in there !!!

Matt93SE

iTrader: (44)

DOH!! I was afraid of that.
Looks like your heater core may be going out. The airbox is directly above the ECU and the heater core is to the side of it, blowing air into the box over the ECU. When the heater core goes, coolant often drips into the airbox above the computer and then gravity does its thing.

I think I still have a US-Spec ECU for a VG30E auto in my garage. I'm not sure what difference there is between ours and yours, but if you need it, I'll send it to you for the price of shipping.

Porky

Thanks for the information Mike - I have a strange intermittent issue with my 94 Veggie, and i'm going to check the grounds while I'm at it.

LQ91SE

My CTS was causing my car not to start...The cooling fans on full blast (on a cool engine) as soon as the key was turned on was the key indicator here. After 20+ years (and 280,000 miles) the contacts were pretty corroded. A $18.89 part from Advance Auto (they stock the part) and I'm back on the road.