F355 Challenge - low oil pressure at idle & slightly jerky acceleration

I have a F355 Challenge and recently when idling at a light (idle around 1K RPM) the oil pressure is on the second line and occasionally dips to the first line and the red light blinks for a split second.

Car feels like it would die but then it picks back up.

I have a straight back exhaust and I think (pretty sure) the O2 sensors are disconnected. Could this be due to the car running open loop?

Oil has not been changed for about 1-2 years (but only ran the car about 150-200 miles during this time = shame but understandable as I have a 2 year old son). It's about to be fully serviced...

Separately, when running on the road, between 2-4K (or 2-3.5K) RPM I have a very very slight hesitation, felt in the gas pedal, almost like the car had a slight misfire.

Obviously no codes. OBD1 car.


Thoughts or pointers highly appreciated from the experts here.

Thank you all.

 

First step: Check the oil level

 

I should have mentioned that the oil level is in between min and max and the oil is clear.

 

Likely a bad sender then. It could be the pump but I doubt it. It wouldn't hurt to clean / check the wore connections of the sender.

 

Well the car stutters very slightly so is the sender a feedback loop or just a display issue?

If it's a display only for the gauge then this can't be it because the car does feel different very so slightly... I would have said ok if the car behaved normally but the oil indicator was low.

 

I had oil pressures issues simular to yours. Hooked up a mechanical gauge which showed pressure was fine, the gauge was the problem.
Turned out to be ground at the back of the gauge.
Everything's fine now.

I would not run the car again until you verify if its a real oil presure issue, that would be the fastest way to burn $20,000


Sent from my SM-G930P using Tapatalk

 

Cool on the Challenge, they end up modded from the drivability BS street machines have

See if you have the 02 I would say you do.

Most likely fouled plugs or some bad gas. I would send the injectors out for blueprinting also


I just love working on mine without those pesky codes, keeps me in tune with my tune up but I'm working on that in therapy

 

So to check the pressure with a separate meter it would be hooked up where the current sender is and it would confirm the pressure?

What external meter did you use if you recall? I'd like to have that as an option and verify the sender.

 

Thanks for the tips -- the car is simplified and I'd need to indeed check the o2 loop, as I recall a few years ago when I got the car I remember some of the dash lights were taken out (less removed) which masked any codes

I know that on this particular car with a straight back exhaust the car is really not that happy at low rpm or idle and I get some backfiring and poor performance. Loves to be at 4k rpm and above.

If there are no o2 then the open loop would explain the symptoms I'm seeing?


Thanks a lot

 

What oil are you running and hiw hot was the oil??

 

I am running the Ultra 5W-40 by Penzoil, which I understand was the Shell formulation. The car is *not* used on the track. I don't recall the oil temperature but based on the gauge it was not off the charts high (I would have noticed).

I was going to change to Rotella T6 oil which has the sulfur additives? and has seen good reviews on my next oil change - thoughts?

 

Also could these be symptoms of bad gas? I had about 3/4 tank when I left and this gas has been in there for more than 1 year but with the appropriate stabilizer. I got to a gas station (Shell) and filled up about 5-6 gallons to max.

This happened after I filled up.

 

Sounds like bad gas to me. Siphon that gas out and replace it. Also use "mechanic in a bottle" in the new fuel to stabilize and CLEAN out the system. Run it and then let it sit. It takes a while but it will clean the old varnished gas out of areas such as the injectors that will be sticking. Challenge cars tend to sit around for long periods of time. The fuel filters may also need replacing.

 

.

 

I have just an autometer universal gauge literally sitting on the center console for testing only. I removed the OEM sender and hooked this up. The OEM sender is very hard to remove, I had to make a tool
You need this fitting to hook it up "R7965 Adapter Bushing - 1/8 NPT female x M18 X 1.5 male"

 

Yeah get that old crap out

If I let cars site I put race fuel in them, very stable stuff

 

Great thank you all -- one more tip since it looks I Need to do this first - what's the best way to get the gas out of the F355?

 

Also on the external oil pressure gauge, is it just as easy as having this universal gauge hooked up with the appropriate adapters to where the oil sender goes into?

https://www.summitracing.com/parts/atm-3321/recommendedparts/department/fittings-hoses

Does the oil sender just provide a gauge output or does it also feedback into the ECU for any reason (closed loop)?

 

The OP's description sounds like the problem is not with the op gauge/sender but what is causing the idle to drop down? Sounds like the gauge/sender are doing what they are supposed to do. We need more history and that will lead to a potential direction which will lead to some diagnostic pathways and eventually a solution.

 

What info can I provide to help diagnose this further...the only thing I had mentioned was the car sat with older gas (which was stabilized - maybe not that great) and then this is a symptom of running it.

What other details can I provide, please advise as I'd be more than happy to.

 

I have a straight back exhaust and I think (pretty sure) the O2 sensors are disconnected. Could this be due to the car running open loop?
INSTEAD OF BEING PRETTY SURE THE 02 SENSORS ARE DISCONNECTED WHY NOT CHECK TO SEE IF THEY ARE OR ARE NOT?
are they disconnected?

Obviously no codes. OBD1 car.
WHY DO YOU WRITE "Obviously no codes.?" OBD1 PROVIDES CODES.
do you have any codes?

 

Honestly, I've never, ever had an issue with "bad gas". I've let stuff sit before (not Ferrari) for a long time with zero issues and zero stabilizers.

Not saying it can't happen, just in my experience, it's never been an issue.

 

I apologize, I will get this information and report back. The car is stored at my vacation home so the earliest will be this Thursday/Friday that I can report back.

What I meant by no codes - no visible codes or dash lights but I will have to run the OBD1 procedure to report back. I am sure there could be some codes.

Will check for the O2s, I know for sure the termocouple probes are disconnected and just hard wired somewhere in the bay to a dummy probe (no cats to measure temp of) but that has been the case for the longest time.

 

That would probably be some of the easier/quicker stuff to check and then maybe be prepared to siphon out the gas and replace with fresh gas, as others mentioned, to eliminate or confirm that as a problem. Having said that, my experience is like Dave's (above), I've had various cars sit a long time with gas in them and no fuel stabilizers (and under less than ideal conditions sometimes) but never had a problem with the fuel.

Then again, you mention it's going in for a full service soon so if it runs okay, just a wonky idle sometimes, and it's safe to drive maybe just let the mechanics sort it out.

 

We still do not know what the oil temperature is/was.

That is why there are two (2) gauges for oil in F355.