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1998 Lamborghini Diablo SV
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Discussion Starter #21
Ok, pulled 2 codes from the car.
p1403: Catalyst temp sensor with low signal less than 200 deg C. (cyl 1/6)
p1407: Catalyst temp sensor with log signal less than 200 deg C. (cyl 7/12)

Codes per Lamboweb. Do these cars have an EGR valve?
 

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someone with a 4 cat system needs to reply, does the lack of the primary cats (and the sensor attached to them) result in those codes?
 

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Discussion Starter #23
someone with a 4 cat system needs to reply, does the lack of the primary cats (and the sensor attached to them) result in those codes?
That would make sense with a catalyst code. But p1403 and 1407 are EGR codes according to a Google search. Don't bad EGR valves cause running issues as well?
 

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Bad EGR valves will cause all sorts of issues, but that should throw its own code I believe. Often a bad EGR will result in very high NOx readings on emissions tests as well.
 

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Discussion Starter #25
Bad EGR valves will cause all sorts of issues, but that should throw its own code I believe. Often a bad EGR will result in very high NOx readings on emissions tests as well.
Other than Lamboweb, those codes are listed everywhere else as an EGR issue. But yes, I don't believe I would have passed my state inspection if these were actually faulty??
 

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There's no guarantee Lamborghini in 1998 used the correct codes. My understanding is they were allowed some time to get fully in compliance with OBD standards due to them importing only a very small number of cars per year, for instance I know my '97.0 does not have per-cylinder diagnostics, only per-bank. Not sure if '98's much less '98 SVs had all the correct codes. You'll need to do further digging.

What did Josh say?
 

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have you tried the key on and off three times trick to see what flashed on the CEL's?

Lamboweb: To retrieve the error code. With the engine off, switch the ignition on off 3 times to the first position (i.e.. not far enough to start the engine, but enough to light up the front instrument panel). The fourth time the key is switched to the on position the check engine light L or R will flash with a code corresponding to the problem detected by the cars engine computer.
 

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Discussion Starter #28
Ran the engine diagnostics. 3 turns of the key, leave it turned on the 4th. I counted 22 flashes which translates to OBDII System Failure. WTH?

 

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L and R CEL lights light up regularly when you have a Quicksilver exhaust. They come on and off intermitently on all my Diablos.

The bucking at low revs is just the high cams, specific to the SV. It makes it very annoying driving at low speeds.
 
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Discussion Starter #30
L and R CEL lights light up regularly when you have a Quicksilver exhaust. They come on and off intermitently on all my Diablos.

The bucking at low revs is just the high cams, specific to the SV. It makes it very annoying driving at low speeds.
@andecorp this is GREAT information. So, aftermarket headers and mufflers while retaining the primary cats will trigger a catalyst code? Is there an O2 bung on the secondary cats that's eliminated when you remove them?
As far as the cams, is that specific to the VVT versions or all SV's? If this is indeed 'normal' behavior for an SV, I'm ok with that. Just want to be sure there's no underlying problem.

Now, that damn starting issue.....
 

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@andecorp this is GREAT information. So, aftermarket headers and mufflers while retaining the primary cats will trigger a catalyst code? Is there an O2 bung on the secondary cats that's eliminated when you remove them?
As far as the cams, is that specific to the VVT versions or all SV's? If this is indeed 'normal' behavior for an SV, I'm ok with that. Just want to be sure there's no underlying problem.

Now, that damn starting issue.....
Correct regarding the O2 sensors on the Quicksilver. I find on all mine, the lights come on either when they are idling too long or I floor it under certain conditions. It could be one, or the other, or both, depending which bank freaks out. They disappear within a couple of minutes of "normal" driving. The codes thrown are always the same - the cat sensors freak out.

The VVT has nothing to do with it, as the VT versions don't buck. It's all SV's and SE's (I'm told, as I've never driven an SE) and supposedly that's what made the Jota's almost undrivable in traffic.
 
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Discussion Starter #32
and go back out tomorrow and see how it runs when fully warm. Does it stumble like you describe? turn it off, wait 5 minutes and turn it back on and see what it does. Try to determine if the problem is only present at warmup conditions, or is it there all the time.
Finally had a chance to take it out for a little bit after work today. Traffic was horrendous, so I didn't get very far, but I did notice a few things.

Car has been sitting since Sunday (5 days). Took a painful 6-7 tries to get the ignition to turn over. Once again, had to apply a little throttle to keep the car from dying. Bucking at low speed was present again as I pulled away. Thanks to @andecorp 's input here, I won't really worry about this too much.

Made a stop for about 2 hours and started up the car again. Still struggled a bit, but I got it to turn over after 2 tries. The bucking was also better after the car was warmed up.

So, the starting issue does improve if the car is warmed up, but not perfect. What should I look into?
 

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Bonehead, how are the fuel pumps? Were they done? do you hear them spinning up prior to ignition?
 

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Discussion Starter #34
Bonehead, how are the fuel pumps? Were they done? do you hear them spinning up prior to ignition?
Don't believe they were serviced. I do here them humming and wait for them to stop before I try to turn it over.
 

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for the fun of it, i would see if the carter motor is advancing the throttle - think you can see that if you pull the top engine cover off. Probably not the issue, but easy to check.

did you find out more information on the 22 flashes? where did you read that was a OBD failure?
 

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never mind, found it. I would find out what is going on there before doing anything else.

maybe clear the codes, and see if that error returns? Clearing the codes wont change the issue, but it will tell you if whatever is going is current happening or a stored error from the past.

also, while your engine cover is off, take a look to see that your vacuum lines are on and in good tact to the fuel regulators. Again, long shot, but worth doing and easy.
 

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Discussion Starter #37
I'll try to pull the cover and take a look later today.
No idea what's going on with the OBDII. I passed state inspection and I was able to pull the catalyst codes, so it's obviously functional. Old cars. Gotta love/hate 'em.
 

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two threads from the past if you you google "lamborghini diablo 22 flashes", not much info there..but still.

you pass the inspection with a CAT error code....so maybe the technician was being nice to you :)
 

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Discussion Starter #39
two threads from the past if you you google "lamborghini diablo 22 flashes", not much info there..but still.

you pass the inspection with a CAT error code....so maybe the technician was being nice to you :)
Ha. I thought that too. Easy for a shop to ‘overlook’ things on a visual, but you can’t fudge the OBDII scan. Results get sent electronically to the state. It is what it is.


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If the problem goes away with temperature and low RPMs, this sounds like an issue with the cold-start inputs. Could be the IAC (Carter Motor), TPS (Throttle position sensor) or associated inputs for the cold idle maps (Coolant temp sensor, and in some cases IAT sensor). The IAC is effectively adjusting throttle position on cold temperatures, and the cold-start maps should be providing initial fuel for engine turnover as well as the coolant temperature enrichment maps (the car gets a lot more fuel on startup, and then fueling enrichment tapers off as the car warms). Any idea on battery strength too? I had a few cars with standalone ECU's that would do all sorts of strange things when Voltage was low. I retuned the car 15 times, before simply upsizing the battery and solving the issue.

If you have an OBD2 reader and can reach IAT, Coolant temps, and TPS make sure they're accurately true positions. For TPS maps too, be aware it may rad 0-5% of so, and most ECU's consider some small variance for "idle maps".
 
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