1993 J30 Starts to Backfire When Engine Warms Up/Sometimes Will Not Start

[KypBaker]

I recently obtained a 1993 J30 which is in pretty good condition. The only big problem is with the erratic way the car runs. For instance, I drove it for the first time today for about 20 minutes (it was a Christmas gift) and it ran like a dream. Acceleration was quick, the engine was smooth, handling was great. I brought it back and parked it for about 10 minutes and when I went to start it again, it would not start. The engine would turn over and all the electronics would come on, but it would not start.

I have also been told that the car will start to backfire and the engine will sputter if it is run for about 30 minutes or more. It has already had an oil change and a trasmission service. It has also been given a diagnostic at the Nissan dealership. They couldn't figure out what was wrong, but suggested replacing the ECM and the Power Transducer, as well as the Coolant Sensor. Obviously, I don't want to buy these parts from Nissan on a whim, because they would be about $1500 brand new.

Has anybody had a problem similar to this? If I do replace these parts, would you recommend a place like Pull-A-Part or another parts car?

[yodawill2000]

You might try the flooded procedure.Hold the gas pedal to the floor and keep it down while cranking.If it starts it will be rough till its burned up the extra fuel.Black smoke ect.If that works you might need to check for a bad injector O-Ring flooding a cylinder after shut off.

Also smell the Oil dipstick and see if you smell Gas.

[driverdriver]

The J has never liked short trips. The engine is not designed for it. Always fully warm up the car before driving off. When the temp gauge has moved to the center, its warm enough to drive. Don't plan on doing short trips, it floods the engine and leads to a no start condition.

I would pull codes from the ECU (there is a procedure for it in one of the forum "stuck" items) and report back.

A $1500 repair on a 16-17 year old luxury car is not uncommon. The parts have detiorated/failed due to age.

[KypBaker]

We tried to start it under the assumption it was flooded, but it was a no go. I have a good handle on flooded engines as my former car was a Mazda RX-7. That rotary engine would flood if you looked at it wrong. It seemed more like the engine wasn't getting any fuel or maybe it wasn't firing completely.

The weirder thing is the car backfiring and sputtering AFTER it is warmed up. That seems to be contrary to common sense. They have a J30 in stock at my local Pull-A-Part, so I'm going to run over there to see if it still has an ECM and power transducer (what is that exactly?). Hopefully, that will remedy the problem.

Another suspicion we had was about the ignition switch. It seems to be really loose. There seems to be a lot of wiggle room once the car is on and it is really tight from the off to accessory position. Could bad contacts in the ignition be causing problems in the engine?

I really appreciate the help. Once I get this engine problem solved, all the remaining work will be cosmetic. I can't wait to get her on the road.
Modified by KypBaker at 10:07 PM 12/26/2009

[Victor]

I don't believe it is correct that one must warm up a J30 before driving it. I have 196,300 miles on my 94 J30T and have never warmed it up before driving it, and make many very short trips, and it always runs fine without a warm up.. If one has to warm up their J30 before driving it there is something wrong specifically with your J30, not J30s in general. Maybe in sub-zero temperatures it would be desirable to warm it up, but under normal conditions it would just be a waste of precious fuel.

[yodawill2000]

One must understand the properties of motor oil.Until oil reaches its determined temperature your wearing out the motor (Main bearings and Rings/Cylinder walls) prematurely.Don't post your opinions till you know your facts sir.http://www.bobistheoilguy.com/...id=64Note the third row down on "Cold Start"

That would be below 190 ish degrees Fahrenheit

I would think since you frequent the Q45 forum you would have learned some of Q45TECH's wisdom.Guess not.


Modified by yodawill2000 at 3:44 PM 12/27/2009

[driverdriver]

Well said Yoda!

I've had my J for well over 13 years, I know other people with the VG30DE engine in both the J and 300zx application. These engines need to be properly warmed up to perform optimally and hate short trips. It's well know that they flood. There is nothing wrong with the engine. That's simply how VG30DE was designed.

Q45tech will concur as well as other Nissan techs on this board past and present.

If you not warming up the engine properly on a 15-16 year old car, your damaging it.

[Victor]

Well if having 196,300 miles on the original engine with never any problems other than a radiator hose and a fan belt and normal maintenance as prescribed in the owners manual is wearing out an engine prematurely I don't know what to say. My engine is still going strong and I never warm up my car before I drive. Where in the owners manual does it say to warm up the engine until the temperature gauge reads half scale before driving? And where does it say this car was not designed to make short trips? In fact if every time you drive you first warm up your car for say four minutes how much of the useful life of the car have you used up by running the engine when not really needed. So assuming the average person starts his car maybe lets say conservatively three times a day, over the course of the year you would start it over 1000 times, so if you idled it for four minutes warming it up each time you would use 4000 minutes worth of gas and extra wear on the car's engine.BTW, I notice you live in Canada, where it is much colder than most of the continental United States, so what may be good advice for areas where it is below freezing is not necessarily good advice for most of the readers of this board, especially the original poster who lives where it is much warmer down south in North Carolina.

Modified by Victor at 4:57 PM 12/27/2009

Modified by Victor at 5:02 PM 12/27/2009
Modified by Victor at 5:05 PM 12/27/2009

[1994 infiniti j30 190+]

i agree with victor cause i have a 94 j30 also with 195000 original motor and i only drive about a mle or so to school and back all the time and it never warms up by the time i get there so warming up an engine befor you drive would be a waste of gas and waste of time. now even though my car has overheated three times and stalled fom one of those times my car still runs great besides an injector failing off and on and exhaust leak. so warming up and engine befor drive = waste of time, gas, and money.

[yodawill2000]

~~Shakes head~~I think you guys missed the "Revving" the engine part..

I usually warm it up for about 4 minutes, then drive under 2 k till I get fully warmed up.That happens to be about when I get off the side streets to a main road.Idling doesnt wear the motor out !!!Its revving up before the oil reaches operational temp that is the issue.If wasting a dollar if that much of gas warming up is an issue your in the wrong car !!!

[Victor]

DriverDriver, this is what your own Canadian government has to say about warming up a car and engine damage due to idling.

What Miko said. Here's what the Canadian environment ministry has to say:

•An idling engine releases twice as many exhaust fumes than a vehicle in motion. •If every driver in Canada avoided idling for 5 minutes a day, we could prevent 1.6 million tonnes of carbon dioxide from being emitted. •No more than 30 seconds of idling is needed for oil to circulate through your engine. Many components, such as the wheel bearings, tires and suspension system will only warm up once the vehicle is moving. •Restarting your car many times has little impact on engine components, adding only around $10 per year to the cost of driving, money that is recovered in fuel savings. •Ten seconds of idling uses more fuel than restarting the engine. •Idling can damage your engine since it is not operating at its peak temperature where fuel is completely burned. Fuel residue from incomplete burning can damage engine parts. •Idling a vehicle for 10 minutes a day uses an average of 100 litres of gas a year. If gas costs 70 cents a litre, you will save $70 per year, just by turning your key. •During the winter, Canadians idle their vehicles for a combined total of 75 million minutes/day. This is equal to a vehicle idling for 144 years. Although we idle our vehicles about 40% less in summer, we still waste an enormous amount of fuel and money. •A block heater warms the oil and engine coolant, making it easier to start your vehicle and improving winter fuel economy by as much as 10%.

[driverdriver]

Read the notes on the Ministry of Transportation website and NRCAN (Canadian Ministry of Natural Resources) its applicable only to vehicles built since 2000 and not before.

I've worked in and around the auto industry for 15+ years. Currently one of my clients is an automaker. I rub shoulders with good people in powertrain engineering almost every day. I know what I'm talking about.

This is an open discussion forum. If you don't want to warm up your vehicle your entitled to that opinion. I respect that. More power to you.

[KypBaker]

Well, warming the car up is definitely not the problem in this case. I ran over to Pull-A-Part today, but the J30 there had already been stripped clean. I decided to crank the car and just let her run until the problem developed. Sure enough, the engine started vibrating heavily and sputtering about 10 minutes after the temperature gauge reached around half-way. The whole process took about 25 minutes.

The dealership recommended replacing the ECU and the Power Transistor Unit. Both have been replaced independent of each other in the past, but not at the same time. Still when the units were replaced, it didn't help the problem. I'm going to try ordering a ECU off Ebay just to test it out anyway.

I've been looking around further as to what else could cause this problem. I've read a couple things pointing to the crankshaft or camshaft position sensor. Could the engine heating up cause this sensor to malfunction and if it did would it cause a problem like the one I described?

[yodawill2000]

The CS is simply a optical sensor and a timing wheel with small slots.I suppose it could have a heat issue but it would have to be cracked or something.

Does the Check engine light come on when it starts sputtering ??Have you pulled the ECU codes yet ??

[KypBaker]

I pulled the codes from the ECU today, but all it gave me was 55. That's the code for everything is working.

I pulled out the the Power Transistor Unit and checked it for continuity. It was good. I attempted to pull out the Crankshaft Position Sensor, but it was difficult to get to.

I grabbed some of that electronics freezing spray that you use to diagnose parts that you think are overheating. I started up the car and waited until it started acting up (20 minutes like clockwork) and then sprayed every electrical part I could think of, but nothing helped.

When the problem first starts, the car will idle fine, but you can't get the engine to rev much higher. You can press the accelerator clean against the floor and it'll just cough and sputter at around 1500 rpm. It'll keep running until I shut it off, but once I do, I more or less have to wait until the next day to start her up again.

I talked to somebody last night who suggested that it might be the catalytic converter becoming clogged up and causing exhaust pressure to build up. Do you guys think that could be the cause?

[fargonaz]

I would check the TPS(throttle position sensor) when the engine is warm. Even if you do find that the TPS is the problem and depending on the severity of the backfiring you should check your MAF (mass air flow, first item with an electrical plug between your air cleaner and the engine) sensor also.

As always, Good Luck!

[yodawill2000]

I'm not an exhaust pro by any means but if the cats were clogged I cant see it waiting 20 minutes before acting up..Very strange symptom indeed.

[KypBaker]

I replaced all the spark plugs today using the OEM plugs. I noticed that whoever replaced the plugs before didn't use the OEM plugs and there is no telling how long ago they were replaced. I fired up the engine and waited, revving it a few times after it was warmed up, and the problem started again 20 minutes into running. This time I was actually able to rev the engine smoothly up past 1500 once the problem started, but I was only able to do it once. I shut the engine off and this time I was able to crank it again. The problem was still present after the engine restarted, but this is the first time I've been able to restart afterwards.

The MAF sensor has already been cleaned, so I think it is good. The TPS sounds like it could be a candidate. How would I go about checking that part?

[yodawill2000]

If you havent already .Download the Service manualhttp://www.nicoclub.com/FSM/J30/

The TPS diag/adjust procedure is on EF-EC page 225.

The Service manual is priceless with diagnosing issue's.

[KypBaker]

I actually have a print copy of the service manual. It is definitely useful. It's just a little hard to find what you want in it. I wish they had an index in the back.

Anywho, I checked TPS before and after the engine had heated up and the readings remained constant. The engine once again had the same problem. Another thing I noticed this time around is there is a grinding sound when you try to rev the engine while the problem is occurring. At idle, the engine sounds fine. Then I step on the accelerator and the engine begins to vibrate and jump and there is occasionally a sharp grinding. I'm not sure what that could be.

I also check the temperature difference between the in and out pipes of the catalytic converter. I was just measuring the external temperature of the pipes with an infrared thermometer, because that's all I really had at my disposal. Once the engine was warmed up and the problem started occurring, there was about a 100 F difference between the in and out pipes. They weird thing though is that the in pipe was hotter than the out pipe. Aren't the exhaust gases supposed to heat up in a catalytic converter, so it can burn away the bad stuff?

[yodawill2000]

That would be my guess.Man this is a weird one.Driver.Can you get Stevie or one of the other Techs to chime in ??Im really curious now if this is a Cat problem.Kyp.Did both cats have the same temp differance ?

[KypBaker]

Both of the catalytic converters had the same temeperature difference. They had more or less the same temperature readings too.

Both were about 215 F on the in pipe and about 115 F on the out pipes.

[swimshark]

Hmmm...I am sorta stumped but I'd check the IACV and other vacuum hoses.

Try checking the fuel pressure regulators.

What type of grinding noise is it and can you pinpoint to where it is coming from?

[KypBaker]

The ECU that I ordered came in today, so I swapped it out for the old one. The car wouldn't even start. So, I thought that maybe the computer that I had ordered was bad (I got it off ebay for cheap), so I replaced the old computer. The car still wouldn't start. The car normally doesn't start again until the engine cools down after the problem has started, but I haven't touched the car since this past Saturday.

The engine will turn over and the car will backfire occasionally. There will also be an occasional grinding sound as the car tries to start. It only lasts for a second and happens right when the engine sounds like it's going to come on. I'm not sure what the sound was and I don't know if it's related to the main problem I've been having, but I do know that I can't test if the ECU is the problem if I can't get the engine started. Any ideas?

Also, I'm going to have much less time to work on it as I'm going back to school tomorrow and will be 3 hours away.

[KypBaker]

Well, I've finally made it back down from school. I'm still not having any luck with the car. I'm wondering now if it is maybe a fuel pump/fuel system problem. I want to check the fuel pressure, but I can't find where to hook up the gauge on the fuel rail. Can anybody point me to where the test port is specifically. All the manual says is "attach a fuel pressure gauge", but doesn't tell you where to do it.

[1994 infiniti j30 190+]

check in the service manual on page EF and EC 230 tell you where and how with a picture. if you cant get it to start take out one spark plug the tap the key to see if the cylinder is flooded a little or not if one is you have an o-ring leak. also check for spark. check your o2 sensors and knock sensor to see if those are working right
Modified by 1994 infiniti j30 190+ at 7:39 PM 3/17/2010

[GerryO]

Worthwhile reading and a lot to be accomplished by simply disassembling and cleaning a number of items.

http://home.swipnet.se/e-solutions/IdleTech.html

http://home.swipnet.se/e-solutions/IdleTech2.html

http://www.zhome.com/ZCMnL/PIC....html

If I let my J30 sit for too long (3 to 4 weeks or more), I sometimes need to resort to the accelerator held to the floor while cranking starting method. I think something inside the IAC/AAC valve is sticking, as I haven't yet removed disassembled and cleaned mine, and all my injectors are almost new.

[swimshark]

yah try the first link GerryO listed. i was having crazy idle at times since ive doen the manual swap. i took off the iacv and cleaned it out and lubed the parts up with wd40 and it idles smooth now.