Starting problem 97 I30

[Garret]

Hi All -

First, the caveats: The car has 232,000 miles on it & still has the original engine. Knock Sensor & 1 O2 sensor code have been showing for about 12-15 months. If I run premium, the knock sensor code can be cleared & will stay cleared, but I'm cheap... I've owned it since 145,000 and done nothing except normal maintenance. Replaced the spark plugs 2 days ago & checked (visually) all connectors to coil packs & what sensors I could easily reach/see. New air filter & MAS is clean as a whistle. (Side question: how can a whistle be clean when someone's spitting in it all the time? ;-)

2 weeks ago the car started getting hard to start. Previously, the car has always started close to instantly (even with the 2 codes & no matter the temp - minus 40 to +90); now it cranks over fine, but the engine coughs & barks as if the timing was WAY off. If I catch it just right, it'll (eventually) start & then run just fine.

The car is a 5 speed, so I can bump start it (coasting down a hill). If I do that, it starts instantly & smoothly.

Once started, the car runs perfectly - smooth idle & normal power.

Battery is one year old, starter draws about 50-60 amps (seems normal in my experience) & battery voltage while cranking stays close to 12 (11.8 is lowest I've seen).

Any thoughts?

Thanks!

[maxhopper]

If you only have this problem when starting it conventionally, I would say it's a starter issue.

[Garret]

I always forget something...

New starter 5 days ago - symptoms are unchanged. Both starters turn the engine over just fine (OK - the first one did until the coughing/backfiring killed it), so I don't believe it's a starter issue.

I do wonder if there's something in the starter circuit that changes how some sensor reading (crank sensor maybe?) is dealt with - but I don't have access to any info like that.

Thanks for the reply!

[maxhopper]

I'd check the fuel pressure next. Hook up a pressure gauge in line between the fuel filter and the fuel rail.

When you turn the key to on (without starting it), and the pump primes the system, you should have approximately 43psi.

At idle you should have 34psi.

If your readings are below these levels, I would try changing the fuel filter.

What kind of spark plugs did you use for replacements?

[Garret]

Hi Scott -

Thanks again. I will check fuel pressure, although why would the car run OK after starting if the pressure is off?

I did replace the fuel filter last week, but since it made no difference I didn't mention it. Same with air filter.

Plugs. The previous set was NGK (my favorite brand), but since they had 60,000+ on 'em I changed them - even though they looked perfect. The new ones are AC (hey - what I could get locally & on a Sunday). Changing the plugs made no change whatsoever.

Garret

[maxhopper]

It could possibly be an issue with the pump not making enough pressure when it primes the system for starting; but once running, it maintains enough pressure to keep it running.

I would also replace the bad O2 sensor while you're at it. You can find them for a good price on http://www.sparkplugs.com or http://www.oxygensensors.com.

I don't recommend using anything but NGK plugs in the VQ engine. Many people have had problems using other brands of plugs.

[maxhopper]

By chance are you loosing coolant, but don't see any leaks?

[Garret]

You're thinking head gasket(s) I bet....

Nope - no coolant loss (but you did make me look in a big hurry!)

I don 't have a pressure gauge that'll do FI type pressures - so it'll be a day or 2 before I test that.

Thanks!

[maxhopper]

You're thinking head gasket(s) I bet....

Bingo! I'm having an issue on my Maxima with a small leak around cylinder 1 or 3 (dumping straight into the cylinder), and depending on how I park (uphill/downhill), it will give me a little trouble when starting.

[Garret]

Thought so.

If your head gasket is leaking, aren't you concerned about corrosion in the aluminum? Don't know 'bout Maximas, but Saabs will eat away enough metal to need welding in a couple of months of a very slow leak. Then there's the fun when it blows out into an oil passage....

That's why I checked my coolant immediately after reading your post ;-)

[maxhopper]

The only thing I'm really worried about with my leak is the gasket totally letting go and locking the motor up. I'm currently looking for a replacement motor and transmission (mine is slipping between 2nd and 3rd) to drop in.

[Garret]

At about 219,000 my 5 speed died (running non-synthetic 90 wt @ 40 below, dummyhead that I am). I got a used one (incl. locking diff) for $600 from Gorham Auto Parts Gorham ME:

http://www.lkqcorp.com/locatio...te=ME

6 month warranty & very nice people. They have locations all over the US.

Other yards wanted as much as $1800 for it - with lesser warranty.

[maxhopper]

Thanks for the link bro, it's much appreciated!

[Garret]

OK - I did the pressure test.

35 @ idle, goes up to 42-44 upon acceleration. Seems about right. However, I did notice that there doesn't seem to be a working check valve, as the pressure falls of to zero in about 2-3 seconds when I shut the engine off.

I'm far more familiar with Bosch injection, but it seems that this car should have a check valve also.

When bumping the starter a couple of times, the pressure comes right up - as it does in 1 second when cranking. So - the starting problem still occurs - even with good pressure, so I'm thinking it must be something else.

I just did a 300 mile trip & the car ran beautifully, except I noticed one thing: driving @ 25 mph (had a cop right behind me ;-) in 3rd gear (~2000 RPM), there is a noticeable off/on lurch as I move the gas pedal from accel to decel - as if fuel delivery or spark was cutting off for a split second. Throttle position sensor maybe?

Anyone know where I can get specs for testing various sensors on this car?

Thanks!

Garret