Possible DIS failure?

Holiday

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So I had random starting issues I thought was fuel related so I brought it in to my local auto shop. They said it was mu spark plugs and so changed them and also the fuel filter. Car ran fine quick jaunts around town. Then my raditor sparang a leak so I brought it into the shop and had a new rad put it. Next day I went on a long trip, highway driving. Noticed the car seemed a bit sluggish accelerating particularly off a stop. About 100k out I started getting on/off CEL. This is new. Car ran poorly with the CEL on. Kept going on/off till I reached my destination. I wondered if it was bad gas or water in my tank or perhaps the new sparkplugs weren't working out. Put in some more gas and some fuel conditioner.

Next morning it was colder than usual and the car had a rough idle upon start. Eventually stabilized but the stalled out at nearest stop. Managed to get the car going again and once warmed up it was fine. Perhaps it was a fuel line freeze(?) On the road 20 minutes and the CEL came on as the day before. Car ran like it was in limp mode. I was thinking it was misfiring for some reason. Then another 100k or so the CEL dissapeared and the car ran perfectly. It's been running fine ever since.

Ran codes when I got home:
114
118
173
177
542

Some codes might because the car wasn't warm enough when I did the KOE test. Also some codes might have been triggered by a misfire. KOER test was just 111 twice. I'm gonna clear the codes and see what pops up again but I'm wondering if it's intermittent DIS failure. If so should I replace right away or try reapplying thermal paste? Odd thing is that car is running fine now. It's a mystery.
 

rubydist

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114 = intake air temp sensor out of range
118 = engine coolant temp sensor is high / open circuit
173 = oxy sensor right is rich
177 = oxy sensor left is rich
542 = fuel pump issue

These codes should be attacked from lowest number to highest number. 114 + 118 tells me that you have a bad power or bad ground to the circuit that runs the IAT and ECT. These engines will never run right with 114, so you have to find and fix that wiring / connector issue first.

Once you tackle that issue, the rich codes will likely go away on their own. The 542 gets set any time the engine stalls, so you can just ignore that one.

As you can see from the codes, there is nothing related to the DIS in these, so you are wasting your time / money chasing that.
 

luigisho

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First impression is I agree with rubydist. 114 is usually bad news for correct running. I have to look at a wiring diagram and see if the IAT and ECT run on the same circuit. Clear the codes, run it again to confirm, and plan an attack
 

Holiday

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Thanks, going to clear codes and read anew. Curious if the issue with temp sensors might be related to new radiator install, perhaps something was not fastened or connected back up correctly. Still curious as to why the car is running fine currently, as in what happened of its own accord to stop throwing up the CEL and run the car normally.

*Quick note: My car has an immobilizer. After the radiator change the immobilizer stop requiring a code. It's still powered it just no longer needs me to enter a code to start the car. Wondering if that might shine a light on my issue.
 
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Holiday

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Cleared the codes, drove around town running errands for about 15min or so. I did have one start issue that required me to hit the gas pedal to fire up, other than that seemed to run fine. I'll also add I had some idle hunting for quite awhile after I reconnected the battery and started the car. I assume this was due to the computer relearning, though it took longer than I thought it would for the idle to level off. Ran codes again and nothing came up at all.

I actually brought it into a shop a couple weeks ago to investigate why I had random start issues that required me to hit the gas pedal to get the car to fire up. I thought it was fuel related, they said it was my spark plugs and changed them. Now it seems I'm back to square one on that issue. Also my immobilizer was offline when I got the car back from the shop, didn't have any start issues again until I detached battery for 10 mins, reconnected and the immobilizer went back online so I'm wondering if there is something related to that. Again though it's a random issue happening every 4th or 5th start.

Still have no idea about why I got the on/off CEL on my earlier road trip with the car, feeling like it was in/out of limp mode, nor do I know why it just cleared up on it's own. I haven't driven on the highway after clearing the codes so perhaps I need to drive the car longer for the issue to reemerge. Currently no CEL and no codes which is rather annoying trying to figure out the issue(s). I do wonder if it's a cam sensor or crank sensor issue but I assume I'd get a code for that (?). Also perhaps the idle air controller but again I assume I'd get a code for that as well.
 
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luigisho

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Well, incorrect air temp sensor input makes the fuel calculations off for start and running so I would be looking at that 1st.

I also hate aftermarket remote start or immobilizer or anything that complicates igntion..just personal preference. I remember installing a toggle switch to disable start under the dash back in the 80's but that was easy enough to remove or bypass in a pinch.
The code popped for a reason. Maybe intermittent malfunction. It is a cheap sensor at the bottom of the intake air box. If you get lucky it's just that. If not then when it's acting up again you might have to trace it to bad wiring or even PCM.
 

rubydist

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My experience is that it is never the actual iat sensor, it has always been a wiring or connector issue somewhere in the harness.
 

Holiday

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Thanks for the help. Gonna go back to the shop tomorrow, check/clean the connections. As I haven't gotten any new codes as of yet hopefully something will pop up soon to send me in the right direction. Looking at changing the cam sensor as well.
 

Holiday

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So 114, 173, 177 popped up again so I have to get the O2 sensors checked. As I have MAF cleaner I decided to clean the MAF and see if that helps.
 

rubydist

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Please read this earlier reply again:

114 = intake air temp sensor out of range
118 = engine coolant temp sensor is high / open circuit
173 = oxy sensor right is rich
177 = oxy sensor left is rich
542 = fuel pump issue

These codes should be attacked from lowest number to highest number. 114 + 118 tells me that you have a bad power or bad ground to the circuit that runs the IAT and ECT.

These engines will never run right with 114, so you have to find and fix that wiring / connector issue first.

Once you tackle that issue, the rich codes will likely go away on their own.
 

luigisho

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I think the 114 affects the a:f ratio so maybe the O2s are not malfunctioning but reading incorrect calculation of mix for combustion. The air temp sensor is the 1st air monitoring sensor in the chain, so O2's will not impact air temp sensor but the other way around is likely. MAF is upstream from air temp sensor and measures what is says flow of air mass. Cleaning it won't hurt anything but I really think the 114 is the primary problem here.

ahhh he beat me by a few second while I was typing
 

Holiday

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The IAT sensor is going to be checked along with all other relevant sensors. Also isn't the IAT sensor located in the MAF sensor?

On another note curious what this sensor or otherwise that is dangling. Seems to me it should be fastened somewhere. Perhaps coolant related, a tube runs off the head and goes down to connect a small cylinder which is connected to an electric plug. In the pic I am moving another connector out of the way to show the part in question.

PXL 20221205 204701550
 
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luigisho

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If you open up the stock airbox, take out the air filter and you should see the sensor mounted inside the box. Unless someone removed it from the airbox or put a different intake before the MAF. Some MAF's have an integrated temp sensor but this one is seperate. It looks similar to this.
1670292558122
 

Holiday

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If you open up the stock airbox, take out the air filter and you should see the sensor mounted inside the box. Unless someone removed it from the airbox or put a different intake before the MAF. Some MAF's have an integrated temp sensor but this one is seperate. It looks similar to this.
View attachment 85758
Ok thanks, gonna check that out.
 

Holiday

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If you open up the stock airbox, take out the air filter and you should see the sensor mounted inside the box. Unless someone removed it from the airbox or put a different intake before the MAF. Some MAF's have an integrated temp sensor but this one is seperate. It looks similar to this.
View attachment 85758

I found it. Mine is plastic though.
 

luigisho

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sounds correct. The design is the same but materials vary. You can always tell by the bulbous coated thermistor in the middle.
 

rubydist

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All the oem ones I have seen were plastic housings.
 

Holiday

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So a mechanic friend of mine said that he thought that the o2 sensors coded because the IAT had failed. Then he said he didn't think the IAT sensor was producing the issues I currently have, however he has no knowledge of the SHO. Currently the car has surging idle which eventually stabilizes to degree when the car warms up enough. It does continue to have a tendency to want to stall when at a higher rev range and then I let off the gas. Then it goes back to light surging idle with the car headlights dimming as the revs go down. Also I noticed the parking brake light hasn't come on when parking brake is engaged which happened when I unplugged the battery to reset the computer. It's happened before and I was able to get the light to activate again by unplugging the battery again for 10 minutes. So I'm curious if the alternator is part of the problem.

I'll change the IAT, also thinking about changing the MAF as the symptoms I have also seem to be that of a bad MAF. Then there is the TPS that also may be the culprit. Finally the PCM.
 

luigisho

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You need to look at a wiring diagram. I think the 114 circuit is most of the issue. If you think the MAF is a problem see if unplugging it stops the surging issue. It will go to default and run way low on power but takes faulty metering out of the equation. If better then replace. If same forget about it. The tps code did not come back on the last code pull. If there is a power issue that can can cause weird stuff. I would test the temp sensor, the plug and if there is still a voltage/ground issue then you need to track it back to toward the computer.
 

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