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Discussion Starter #1
My son's vehicle. The alternator failed. He tried to make it to the next exit but it died. He had it towed home and replaced the alternator. The new alternator installation went well, and after that, it ran normal and charged strong, but it wouldn't idle. It would stall if you let your foot off the throttle pedal. While we were diagnosing that symptom, it got worse, and now it will start, but immediately stalls after 1 to 2 seconds. It will keep restarting, but will not stay running. Even with throttle input, it revs, but then dies, each time like somebody hit a kill switch. It sets only one code P1155 which is for a limp home valve malfunction. We swapped the throttle body assembly (which includes the LHV) and no change. We checked the wiring continuity from the LHV to the ECU and that checks out good. The system will not allow my Actron scanner to clear the P1155 code. And interestingly, when we disconnect the battery to hard clear everything, the P1155 returns on the next key on, before even cranking. We are totally perplexed as to what could be going on here. Does anyone have any suggestions for what we could investigate next. Thanks in advance for any advice!
 

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The sensor or wiring is bad but I don't think that's your problem. What does the theft light do?
 

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Discussion Starter #3
Thanks for the reply. I had thought about the theft system. How do I check that?
The key fob seems to lock and unlock the doors and arm and disarm the system like it always has.
Which theft light are you referring to..?
One other thing I meant to mention in my first post is that the tachometer still works properly while cranking, and during the brief (approximately one second) run period. Also, the few parameters that I can monitor on my crude scanner (TPS, RPM, MAF, Coolant, IAT, etc.) appear to be working. But then everything just shuts off like a switch.
What is the normal operation of the theft system when it's activated (to prevent the car from being stolen)? Does it allow the car to start and then shut it down, or does it just allow the car to crank and not start?
Please let me know more about how we can rule out the theft system.
 

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Do you have a symbol of an engine with a key?
I'm thinking the anti theft doesn't kill after 2 seconds like some do.
Maybe @AUTOSPARK can tell us.
 

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Discussion Starter #5
No. There's no symbol of an engine with a key.
I don't think we have that symbol at all.
I don't see it when I key on.
 

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Discussion Starter #6
I just checked the Owner's Manual and there is no symbol listed for the alarm system.
The description of the alarm system only discusses what the alarm will do if it is set off.
There is no mention whatsoever about any disabling of the vehicle.
Could it be that we only have an "alarm", and not a true "anti-theft" system?
 

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Discussion Starter #7
When we lock the door and arm the system, we get a flash from the four turn signal bulbs.
If we hit the lock button a second time, we get another flash and an audible chirp from the alarm.
There are no indicators anywhere on the dash...
 

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Discussion Starter #8
Here's something else that seems interesting:
After it starts and stalls, if I try to restart it leaving the key on, it won't restart.
It cranks very strong, and sputters like it's trying, but it won't start.
BUT if I turn the key off then back on, it will restart again every time.
Of course, it still stalls again after about one second, but it does start.

It seems like something is happening during the "crank" to "run" transition.
I'm not sure what actions take place during that hand-off, but that's how it seems.
It kind of feels like perhaps something is shutting off the fuel pump.
Is there some way I could hook up a fuel pressure gauge to watch?
 

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Ignition switch?
 

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Discussion Starter #10
Ignition switch?
I suppose it could be...
But it doesn't die when I let off the key from the crank position.
It runs for a second or two then dies (stalls).
Is there some way we can check the ignition switch?
 

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I would use a test light or meter to monitor the feeds. I'd like to get a diagram for the starting circuits.
 

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Drives : Nissan NV200 Flies : Rans S6ES
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Sorry I'm late to the party :)
Before you go digging into a lot of electrical diagnosis maybe you could try this very simple test...pull the vacuum hose off the EGR valve. See if that allows the engine to run. The valve is bolted to the back of the inlet manifold, next to the throttle body.

Hyundai 3.5 EGR Valve
450696


If I helped you fix it, why not...

Your support is greatly appreciated
 

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Discussion Starter #14
I removed (and plugged) the vacuum line to the EGR valve, and in fact, that does allow it to remain running.
It runs at 700-730 RPM with 9.8-10.2 degrees at the TPS. With the A/C on, it drops to about 580-600 RPM.
When I step on the accelerator pedal, it does nothing. No response at all. And the TPS remains unchanged.
I still get only the one DTC: P1155 which shows as confirmed and pending.
Also, it smells terrible (I think very rich), like its in some sort of back-up mode for fueling.
What does the EGR valve experiment tell us..?
 

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What does the EGR valve experiment tell us..?
It suggests there is vacuum being applied to the EGR valve when there shouldn't be, which will open the valve. The pistons can't suck fresh air (oxygen) into the cylinders if the EGR valve is open and flooding the cylinders with exhaust gases. So the engine dies due to lack of oxygen.

Did you reconnect the vacuum hoses to the correct ports when you changed the throttle body?

Another thought...is there a good 12V power supply on the limp home solenoid harness connector?

If I helped you fix it, why not...

Your support is greatly appreciated
 

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Discussion Starter #16
I'm pretty certain I reconnected the vacuum lines correctly.
The throttle body has three cast bosses on top, labeled A, E, & P.
The line that feeds the EGR solenoid is on the E (center) nipple.

The LHV did indeed have 12 Volts on Pin #1 when I checked it.
And Pin #2 had continuity back to the ECM (Pin #5 on first connector).
But I will check those again today to confirm that is still the case.
The LHV connector is a two pin connector oriented vertically.
My understanding is Pin #1 is the upper pin, and Pin #2 is the lower pin.
 

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Discussion Starter #17
OK. I checked the Limp Home Valve harness connector again. Pin #1 (the upper pin) has no voltage with the key turned off, and 12.74 Volts with the key turned on. I believe that is how it should properly be.
 

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Sparky will be able to help you with this. I may be able to shed some light if I had some service info.
Can you post the info you are using?
Something to keep in mind is a static test (no load) may not tell you the whole story.
 

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I'm pretty certain I reconnected the vacuum lines correctly.
The throttle body has three cast bosses on top, labeled A, E, & P.
The line that feeds the EGR solenoid is on the E (center) nipple.
Sorry, I'm not that familiar with the 3.5 engine. It was never offered in the Santa Fe here in the UK. I found the photo below on google though and it shows the solenoid hose attached to port 'A' on the throttle body, and the hose from the vacuum regulator attached to port 'E'...
450749


If I helped you fix it, why not...

Your support is greatly appreciated
 

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Discussion Starter #20
That plumbing looks different. We don't have that vacuum control valve.
The rest appears the same, so I may have described ours incorrectly.
Our vacuum line with the green stripe is on the center nipple.
And our vacuum line with the yellow stripe is on the rear nipple.
The center nipple even has a dot of green paint on the casting.
I'm certain this is how it's always been for all the years we've owned it.
That doesn't necessarily make it correct. But it's not today's problem.

Any ideas why I get zero throttle response when it's running now?
I can push the accelerator pedal to the floor, and nothing happens.
Also, the exhaust smells really bad, like it's running ultra rich.
To me, it just has the feeling of some sort of ECU problem...
Are there some additional electrical checks we can perform..?
 
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