[Help] Cold Start OK, change gear and engine dies

First Post. Thank you for help.

My car is 1997 Infiniti I30, first owner. Current mileage is 149000 miles. I did all the maintenance at dealer before 60K mi. After that I just DIY or find a garage to do maintainance. The following is the related history.

05/22/2003, 101700 mi, cooling system flush.
07/10/2004, 123000 mi, self-change 6 spark-plugs (NGK R PFR5G-11). Before that dealer replaced spark-plugs at 60K but not at 30K.
07/16/2005, 142500 mi, self-replace engine oil (Valvoline 5W-30), oil filter, and air filter.
11/23/2005, 147500 mi, self-replace engine oil (Valvoline 5W-30) and oil filter.
11/24/2005, 5AM, engine cold start OK. Changing gear is fine. Drove from San Francisco to Los Angeles for 400 miles. No problem at all.
11/25/2005, woke up at 5AM to do Black Friday shopping. Engine cold started fine. Idle speed was about 1200 rpm. But tachometer moved up and down ranged from 500 to 800 rpm then engine died if I changed gear to any of R, D, 2, 1. "Check Engine" light lit up. Restarted it again. "Check Engine" light went off. It seems fine when engine was started. But once I change gear, it happened again. The problem remained the same even after the engine was warm up and idle speed at 800 rpm. I tried almost 30 mins before I can get it moved. After I hit the road, everything is ok for the day. I parked the car for 5 hours and I can start the engine and hit the road with no problems.
11/26/2005, 10AM, engine started OK. But it died once I change gear, just like the sympton the day before. I have to warm up the engine for 20-30 mins and tried my luck. I took my car to an garage and the technician use a computer to find out it's knock sensor problem. I didn't fix it. And drove from LA to SFO that night. The sympton never happened that day except for the first time.
11/27/2005, car was parked in the garage. The problem happened again. But once I can drive the car, it won't have any problem for the whole day.
11/28/2005, car was parked in the garage. Surprisely the problem was not happening entire day. I added a bottle of Chevron Pro-guard Fuel Injector Cleaner when I pumped the gas.
11/29/2005, car was parked in the garage. It happened again. But this time "Engine Check" light won't go off. And engine will die on the road. I had to warm the car even longer to got it stable before driving to an garage to replace knock sensor and ATF.
11/30/2005, Same sympton happened again when I changed gear after cold start for the first time of the day. But if I warm up the engine to normal temperture, I can change gear to R and idle speed remained at 800 rpm. The difference is: before changing knock sensor, the engine could die even after engine was warmed up.
12/01/2005 and 12/02/2005, Same problems as 11/30. The garage wants to keep the car for a day to check in the morning.

Can anyone give some thoughts? Thanks.

Just found a similar symptom on http://www.automotiveforums.com/vbulletin/showthread.php?p=2713275.

Could Throttle Position Sensor/TPS be the culprit?

...Can anyone give some thoughts? Thanks.

I am thinking that your profession must be record keeping:) ...never seen such detailed description. Good.

One problemcausing issue is IACV idle valve - filled with soot after 60k, yours mileage is 2½ times more. Just clean it, that is easy DIY job. The soot jams the stepper motor: it cannot adjuts idle as you let gas off and engine rpm's drop. To get an IACV idea check the VGE idle valve:http://www.cardomain.com/ride/748507/4

If symptoms NOW have appeared to be more severe when cold, worn TPS Throttle Position Sensor is most probable reason. Easy DIY swap 90$ (or clean; see page6). Follow the links ... http://www.cardomain.com/id/pohjola#links

On top of this, you possibly (?) have intermittently dying ign coilpacks, typical at that mileage. How does the engine die on the hiway?

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[QUOTE=Nahkapohjola]I am thinking that your profession must be record keeping:) ...never seen such detailed description. Good.

Thank you so much for the comments. I think it's more polite to provide as much info as I could in order for people to help.

The car never died on the highway by the way. And I got more constant behavior after one week of observation. When I start the engine in the morning, the idle speed started with 1200 rpm. And the engine died if I changed gear when idle speed at 1200 rpm. However, if I keep warming up engine for 3-5 minutes, the idle speed will drop to 8-900 rpm. After that moment, the engine won't die if I changed gear.

So what made the idel speed drop to 800 rpm after engine warm up? Does IACV (Idle Air Control Valve) no longer control the air flow after that? This makes me think IACV might be the culprit.

I haven't cleaned the soot in IACV nor TPS (Throttle Position Sensor) yet since I don't know where they are. I was trying to post a photo but failed. You links are very helpful if I have done it once. I guess I will bring my car to an garage and see how they did it so I can learn by myself. But could you provide your opinions about previous 2 questions?

Regards,

... I was trying to post a photo but failed...

Pic: First you have to upload pics to a server; lots free album locations... Next, you have to get that address *, type it * here between * -marks...

TPS
Search this forum for TPS. Costs about 90$, easy to DIY change. Located on Throttle Body TB. VGE TPS here: http://www.cardomain.com/ride/748507/6

TPS is used as cold engine input to ECU & A/T. After warmup, its used only for A/T. Try to find detail info for your car via http://www.cardomain.com/id/pohjola#links

ECU controls the engine. It constantly tries to keep lowest possible smooth idle. IACV is the actuator: it adjusts idle airflow with its stepper motor actuated air valve.

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[QUOTE=Nahkapohjola]Pic: First you have to upload pics to a server; lots free album locations... Next, you have to get that address *, type it * here between * -marks...

Happy Holidays!

I searched the forum and found the website to download the FSM (Factory Service Manual) of my I-30. It's very useful and I know where the parts located now.

I had the mechanic clean IACV and throttle body on 12/13/2005. He took off IACV and sprey some air intake cleaner into it. The throttle body was very dirty and he has to sprey the intkae cleaner a couple of times. But he told me he can only clean the area around the valve since the rest is out of reach. They charged me $40 for labor and I think it's easy to DIY in the future.

The mechanic kept telling me the tranmission is gone. It won't help clean IACV or throttle body. I just I have to live with it till it died.

The symptons remained the same. The idle speed is now 1500rpm when I first start it. It was 1200rpm before the cleanup. Is this ok or too high?

After 1 min the idle speed dropped to 1250rpm. The RPM dropped to 4-500 and engine died when I shifted gear to R. If I changed gear to D, it just went up and down between 500 and 1000rpm and very unstable. I have to wait another 3 mins till it drop to 800rpm. Then the car runs ok again.

Kragen Auto parts has the TPS for about $90. Would it help to replace the TPS?

And I wonder if any of those transmission treatment helps. How would the transmission treatment help the car?

And I wonder if any of those transmission treatment helps. How would the transmission treatment help the car?

Start by measuring charge voltage. It has to be 13.8V to 14.7V while engine runs. If its less, correct the problem. Affects 'all' car parts...

The TPS swap is one of the cheapest things u may buy into u car; results you can only guess. I'd give 90% probability based on what u tell (not what I can tst)... Second swap possibility to get over the problem is MAF (600$ ?) or reman 200$. But you may DIY spray clean both; results are good -IF- the problem is dirt.

Tranny:
- Oil mfg gives 20-30k warranty for your A/T oil. I dont know how u changed ATF, but I'd start by total A/T oil change (see above link page 24 what that means).
On that page there is also link to the solenoid service pack: they say help in certain slip & rough conditions. They say cheap & 'easy' to swap; dunno, have still to order their valve upgrade bits.
- Another culprit is A/T solenoid power supply drain; see pages 14&15 what u can do. Will help in some cases...
- Last thingie to do is these snake oils: if A/T replacement is the other option, sure try all of them. Their enhanced friction properties will help in some cases - if problem is loss of friction. If problem is smtg else, might clog/kill. But u never know what u dont know...

...Merry Christmas!

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I did change Transmission fluid on 11/30. The mechanic told me 97 I30 can't do A/T fluid flush. He can only replace it by draining it and replace it. And I am assuming only 1/2 or less A/T fluid was replaced? Is it right? But I check the oil and it's clear after the change.

Your link of changing A/T fluid is very thorugh. I will read FSM to get more information since I still don't understand a lot of terms.

After reading your post on 12/20, I decide to try TPS. I located the TPS according to the FSM and unplug the two connectors. I just clean the two connectors and put them back. Leave TPS untouched. Strange thing happened. The engine didn't die when I shift gears for the next three days. Though the weather is a little bit warm these days.

I still don't know exactly what happened. I need to watch the symptoms a few more days. The bottom line is, I'd better understand my car more before going to the garage. Otherwise the mechanic will keep asking you change parts since that's the way they make money. I spent $240 in changing knock sensor which might not be the culprit.

... I located the TPS according to the FSM and unplug the two connectors. I just clean the two connectors ...


Drain&replace means '1/3 change' as fluid inside system does not come out.
If car has A/T tubes going into radiator, whole change is possible, most dont want to. Some cars have not this feature. Flush is a wrong word: fluid is always circulating in these tubes, fast and under pressure...

Let some other shop diagnose also the A/T. Ask about additives and about the valve upgrade, solenoid pack swap/installation. Additives might help, cheap tst before total overhaul.

TPS
Best scenario is that connectors oxidized. They are easy to open and clean, add contact grease. Laborious, that is why they dont correct that in a shop: 150 connectors with 2-4 pins each, both sides '=2days' cleanup job... Best thing is, only cleanup knowledge is needed.

Knock Sensor swap is ok, they die of age. Typically constant power loss, gas consumption up. No such thing as free (s)miles.

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