@Brnzilla, thanks for the comment and for subbing.Your experience almost completely superimposes my own years ago and is the reason I started taking this approach and sharing it- to help people exactly like you. I am glad you found the channel and I hope it serves you well!

Thanks Joe. As you see below, ScannerDanner himself recently discovered my channel. It's somewhat akin to Miley Cyrus showing up to a 16 year old's birthday party! Well, bad analogy- both ways, but you know what I mean lol.

This was my exactly problem atm so are u saying clean throttle body’,? Mine has died at a stop light and then started right back up and idles hard

Hahaha so true!! man it's so funny but almost always I get these cars with these nasty engine bays that have never been cleaned ever.... yet these new spark plug wires, coils, alternators, or batteries just stand out like diamonds in a goat's ass lol.

Give your wife a fish, at least she has an excuse for the smell.

Hmmm- confused. Seems to me the potentiometer was dead correct since it clearly read the throttle position correctly both before and after the repair.

Well I believe there are two potentiometers. One that sends an analog signal and a fallback which either sends another analog signal or possibly a PWM. Could be that the scan tool read the functioning one? The ECU on the other hand reads both and compares the values then try to come up with something, trouble ensues. Volvo did release an updated software that could prolong the inevitable by changing how the ECU handled the signals. But still, both a good cleaning and the new software is just a stop gap measure. The customer will end up replacing it, or rebuilding it with aftermarket parts. On more of a side note, what I've never really gotten is how cleaning the TB can remedy it, at least for a while. Either you massage the sensor back to life or it's just that it's more sensitive to crud when it starts to go bad. Both possibilities sound a bit off though.

+Frinkbit Sense this was not responded to, I'll take a swing: The TPS reports the position of the throttle plate. As shown by the first test done the reading was a bit on the high side. This is due to the large leak by the throttle plate caused by the carbon build up holding the plate open slightly. Clean off the carbon build up and it will allow the plate(s) to fully close down shut--and it will allow the IAC system to be able to do it's job correctly. The system treated this throttle plate being stuck partly open just like it would a vacuum leak if you think about it. Tries to compensate but all it winds up doing is either setting a code if it goes outside the parameters of the program--Or it attempts to settle down the idle with the IAC system, but it can't fully get the idle under control due to the plate(s) being stuck open. That's why it was surging. I expect if the issue became any worse that it would likely set off the DTC's I say "Plate(s)" due to the fact on some vehicles they have sometimes a single or double bore system. The same theory holds true on those, as they are connected by a common shaft, and any crud blocking one side partly open will hold the entire unit slightly open. That's about as simple as I can make this--and likely it's not 100% the best way to explain it. Just trying to make things simple for the layperson to comprehend.

Do you have the vacuum diagram for the Volvo 740 non turbo.. PCV setup

*rrrrrawwwwwk*

I did it once without removing anything same with evap purge valve on a inline 6 twin turbo xc90. Mine was throwing false crank sensor codes. Ended up being starter wire...

... *five months later* ...

@@gavinvalentino6002 it was indeed what he explained in the video.

+Nathan Bracko Thanks for the feedback. Unfortunately about 2 days after I did this video the owner hit some ice on the road and drove off the road into a ditch totaling the car- so we'll never know how long the repair held up. But she said it drove perfectly until she totaled it lol

She couldn't handle all the newfound horsepower you unleashed ~

Thanks, how kind of you to say!

Good advice Jarin, Indeed as a DIY I indeed find it hard to get more technical material. While it had occurred to me that manually moving the throttle with it plugged in might get my finger stuck, lol, I hadn't considered the possibility of damaging it as I never heard of that. If I had a bidirectional scantool my preference would surely have been to have the computer move it anyway, but to be honest, I was so not expecting this to work that I was figuring I would be replacing the assembly anyway. The car is still running perfectly and I am so pleased that this was fixed without buying anything.

Schrodingers Box Well, you did a fine job sir and you just earned another subscriber.

same symptoms. may or may not be same problem. I would recommend confirming it’s same problem before digging it out.

@@SchrodingersBox Well the engine was loping pretty bad, especially after running for a while. It also has over 200k miles, & has spent it's entire life in NM & AZ. I totally understand your point however, but everything did make sense. I was planning to clean the TB anyways, as that's just something I do when I change the oil. I wasn't able to drop the TB out like I wanted, as some of my tools have gone missing; but I did manage to spray some TB Cleaner into the butterfly valve. I couldn't see any bare metal inside it before I started, cuz it was totally caked in carbon buildup. Now I can see the entire valve & spindle. It's not perfect, especially around the lip; but was definitely good enough to get the loping to stop. 😉 Now to figure out my electrical issue....

I was going to go there but Dr Evil said it would cost .... get this.... $100

Thanks for your support!! New videos coming on there soon!!

no we would not. Yes the open throttle is letting more air in however that air is metered. It’s measured by the mass air flow sensor so there is no fuel trim adjustment from the extra air.

@@SchrodingersBox ahhhhh ok thank you very much!

Yeah as we have mentioned before, Jeff, the diagnosis is the fun part and i could care less about the wrenching. But when you find find you have an hour of wrenching just to fet to the parts you need for diagnosis its an interesting bittersweetness lol. Again thanks for your support as always bro!

Schrodingers Box Yup, I agree again 100% lol..bittersweet is putting it mildly :) For your future reference, and of course I am no Volvo expert, but there is some technical data out there online about this exact throttle body that matches your symptoms. This TB uses whats called "thick film potentiometer" technology which has a fairly high failure rate that causes symptoms similar to what you have on this car. I bring it up only because of my GM experience and the common TB issues with the 2006-2007 ish cobalts, and pontiac waves etc. They would come in for TB DTC's, or intermittent limp in modes, or weird idles and surges. 99 out of 100 times you would follow all proper circuit diag and find no prob and it would eventually lead to replacement of the TB. Sometimes you could clean the TB and clear the code and the car would be fine for another 3 months or 50,000km but eventually would come back with same issue. GM never did release a TSB or software update to the best of my knowledge but we changed hundreds of these TB's at the 2 different GM dealers i worked for and that was the only fix. I started taking these TB's apart and what I found was the "thick film potentiometer" would have one out of 4 tracks that had failed, and this was on EVERY unit i took apart. Basically it would have 4 fingers sliding on tracks like a fuel pump sending unit only times 4. And one of these tracks would have the coating or "thick film" crack and peel off making the finger struggle to make contact, causing intermittent issues. I bring this up because this Volvo year make and model uses a similar 4 fingered thick film potentiometer that apparently has the same failure issues. Here is one article that might be useful home.comcast.net/~donwillson/tech_info.html If this car comes back in the future and the TB is still fairly clean, this may be worth looking at. Yes Im a geek…I know :)

They are like little murder mysteries aren’t they!!!

exactly.

Love those guys!

A video of that catch can would be great.

I would start by looking at how the fuel trim is responding to the idle change to get direction and if there is a response determine if it is a result of the idle changing or the cause of it.

Avery Alexander or if the IAC is stuck open it will bounce off the rev limiter doing the same thing.

No idea. what was your induction data?

Sorry I don't have any data.. I can only see the needle jumping and hear that the idle isn't stable. Car only have old OB(1) interface.

Jon Olafsson I would rather receive a haircut from Justin Bieber than work on another volvo lol!

Check the IAC actual vs desired position

Yeah just give me good old American cars all day man. Especially as a DIY, the specialized tools often ended for some of these kinky models- especially BMW, Audi, etc make these cars impossible to be cost effective to do some procedures. Ironically, AutoTap gave a few more PIDs than autoenginuity did. I need to call AE because my module claims to have volvo enhanced parameters but clearly that wasn't the case at all!!

Please tell me you're joking. I'd sooner watch a car repair video from Justin Bieber.

I'm completely serious about that. And You can also add some "ugh" while undoing those bolts, like Scotty does... If you decide not to, I'm gonna be still watching your videos anyway.

If the deadheaded pressure is only 35 then check voltage drop on the pump and if less than .6V I would replace it only then.

No idea. what data do you have?

Oh... my... god.... nice catch!!! Wow. I am speechless. In fact it is Within Temptation, I forgot the track though. Too bad Tarja didn't stay with Nightwish in my opinion. She's irreplaceable. Nemo- possible the best song ever in world history.

What was your desired vs actual TPS? What is the IAC counts? What data do you have?

Also, just an fyi. These ETC systems will always be slightly spring loaded in the open position. I haven't seen one yet that was fully closed with the key off.

ScannerDanner Yes indeed I did notice that- it threw me off at first but seeing that it was finally able to adjust to full closed position when it needed to (e.g. running with a huge vacuum leak) confirmed there was reason to expect a fix was in order. Incidentally, you are a legend around here- I don't think I have a single video where your name hasn't come up in the comments. FYI, I love your channel and I am a e-book owner and scannerdanner premium subscriber!!

Schrodingers Box cool, I did not know that. Thank you very much! Hope you get some more subs, you're doing a fine job and you've earned it.

You've actually helped me rule out my etm. Totally agree...I need an honest discussion and problem solving not where things are. Yeah that etm position is like a wtf. Anything pre 2000 is easy to work on. Yeah that part is pricy.

Richard Cowtails I've only seen one volvo and I know issues with the idle air control due to carbon buildup are common, I have a video on it.

Schrodingers Box hehehehe. Brilliant! Btw. - I own a volvo. And if you hate those guys, take a look at model 940. But really - do it. Inspect engineering solutions. And the throttle body. And IAC. And TPS. Well, that said, enjoy the simplicity as I do every day. Nice, easy vid, btw.

Inaccurate gauge my guess. The p2 runs higher pressure then p80. Thats why same injectors flow 395cc rather 315cc on 98- regulator.

Mine runs 36psi at idle at rail 45psi at pump..

Ni just carbon build up but that would of been the next thing they have a contact less one you replace the old worn contact one with

That’s normal.

But why car is strugling, jumping idle when push brakes on cold engine? On higher rpms from exhaust goes black smoke, misfire. New spark plugs, new air filter, clean ETM, clean MAF.. nothing changes..

It’s because you are looking where the problem isn’t. Why did you replace the plugs? What data showed this is an ignition problem? I would totally start there. If you found an ignition issue then why are you concerned about MAF?

​@@SchrodingersBoxSpark plugs change was just regular service

Ah so what data from the MAF indicated it was dirty?

Hi 12V. I am not sure what a throttle induction service is but by context I gather this is probably some chemical cleaning of the throttle to decarbonize it. I will tell you that it took a good 10 minutes with a wire brush and a half a can of carb cleaner to remove the carbon. The buildup was clearly preventing the proper backwards throttle movement because it was so dense. If a "throttle induction service" does not involve some actual mechanical scrubbing, I highly, highly doubt it would have been effective in this case. There is no way, in my opinion, this repair would have been effective had I left the throttle body on the vehicle while attempting this repair.

Looks like it would not have worked; Manual cleaning on this vehicle is quite labor intensive. After you had taken half the engine off to get to the throttle body, did you see any rationale why engineers did it their way?

12vgs8606 Other than they just wanted negative attention, no, I see no reason for this design lol. As a matter of fact, it seems particular in this model which is a turbo model,the routing with the turbo induction has to literally wrap around half the engine because the throttle body and turbo are as far apart in diametrically opposite locations as possible. Then again, with the system being electronically controlled I guess there is no reason for it to be accessible. There's nothing to adjust or do with it like with a normal throttle

it is also the IAC. All vehicles need IAC. it’s either through an IAC motor or via the electronic throttle. But it has to have IAC

It’s possible. what was your data indicating the MAP was bad? I would totally start there. Was it direct voltage or PCM output data that showed it was bad?

It was actually the mass air flow that I changed and not the map 🤦🏽‍♂️

Even more critical then since MAF is the primary input- what was your data indicating the MAF was bad? Did you base this on the measured airflow or on a volumetric efficiency calculation?

I’m guessing it’s the fuel pump relay because it don’t happen while I’m driving

why do you suspect the fuel pump? did you rule out the position sensor based on its static vs loaded voltage?what is the fuel pump amperage draw showing

I have seen several models of cars where the O2 sensor only switches while driving. I have absolutely seen the O2s switch on this exact car (not shown in the video though since not relevant to this diagnosis).

Schrodingers Box Driving or not the pattern described holds. Internally the PCM sees it right, but the OBD II data is false...I should back probe the O2 sensors to prove it. :)

+DE Nichols Yes I've had incorrect reporting via generic and advanced obd2 data. Recently I had a Subaru Liberty (legacy) where AutoEnginuity was confusing O2 sensor data. AE seems to struggle with Australian Subarus. The Liberty had a faulty (O/C) heater circuit on the front AFR sensor. AE was reporting extreme current draw from rear O2 sensor (10A) I was able to double check rear sensor current draw (

Winner Winner Chicken Dinner!!!!!! Nice!

Schrodingers Box Headbangers are a dying breed... I cut my hair a long time ago, and nowadays only bang my head when I get stuck on a repair.

Whenever I find myself at a car dealership looking at vehicles and the sales person is going on about all the cool gizmos, I'm looking under the hood and under the car to see how easy it is to work on and how well thought out it is service wise. I'm sure all techs say the same thing as in this video, "Why in the world is it built like this?"

Have you gotten it running well yet, I have the exact same car

@@pelon9794 it was a fuse . now my idle good only after it warms up from these very cold temps. And now my transmission solinoid have stopped. I need $1,400 to get them replaced. ...Uncle Sam is LATE on that money.

That is now how my engine idles after it is warmed up.

You shouldn’t have to. What is the resistance at the TPS showing on idle vs WOT?

@@SchrodingersBox Thanks for your prompt reply ,i really don't have the tool to measure the R. planing to order the VIDA DICE for volvo though.i thought if you have any idea how we can re set the throttle or solve the issue I truly think you site is the best in explaining the root cause of the problem in details .

Yeah sorry that happened but the only thing you can try is let it idle for 15 minutes and hopefully self-relearn. Otherwise you need a scan tool to do it. On some cars just turning the key to ON for 15 minutes without running it and then turning off and idling 15 minutes and then holding it at 1500 and then 2500 RPM for 30 seconds each can do the trick. Otherwise you won’t be able to relearn it yourself.

@@SchrodingersBox Thanks ,I will try it and hope it will works ,

What data do you have? why would you try cleaning it?

@@SchrodingersBox clean the carbon build up on the throttle inlet so the plate can move better. The only codes i have is p0700 a tanny code and p0236 for the map sensor. This hunting idle is driving me nuts ive replaced battery tcv starter coils plugs wires and even the ignition wiring harness i have no air leaks ive looked and took apart the whole engine besides the insides i have a new maf sensor and it still surges hard after its warmed up could it be my coolant temp sensor being bad? I dont have much tools but i know alittle about cars but this idle is crazy it only seems to happen in drive while stopping at lights i just dont get it. Ill be ordering a map this week and a coolant temp sensor tonight i have a 2001 s40 1.9t btw

could be anything. i’d start by testing the MAP output against input variables. But more importantly- whatvwas your MAF dat showing that indicated it needed a new MAF? That’s a total clue there. Was this based on frequency or fuel trim?

@@SchrodingersBox thats the thing i used a scanner from a auto store that gave me codes i checked online and found part numbers for shit ive replaced but the problem is still here i only have limited tools i guess ill need to go to a dealer and get a real read out

that’s my question- what was your data indicating to replace the parts? And why on earth are you replacing the CTS? What data is indicating it was bad? you never mentioned testing it. Trying to follow your strategy here.

autoenginuity.

What is the desired TPS vs actual? 16% sounds high if car is warmed up and idle.

TPS is not moved by anything but the pedal. I guessed the DMFW as an origin but that has been replaced like 8 - 9 K Kms ago. This thing occurs basically when RPM goes down (Closed loop , warm engine) but not always... that's the trick. If that would happen all the time..... would be easier to hunt down the guilty thing...

Yes of course- it is a ETC system. Again- you need to know predertimned desired position to assess if TP% is in optimal idle position.

in my understanding > TPS showing 16% is the closed position... cable has play so that's not an issue. I checked the butterfly valve .. it is closed (well tiny light can pass ...) Will make some cross check by testing my friend car (same engine). If the same % will be shown... then I can still move to the MAP...maybe it has some lag and creates an oscillating loop with the idle valve / crank shaft sensor when trying to set an RPM.

aprt from the Idle... i checked the sort and the long term fuel trims.... Interesting... of course i was using a common Scanner tool and torque softeer via Bluetooth. So... STFT is pretty quick... but the biggest magic is that the LTFT is almost as fast as the STFT (reacts pretty fast). Lets see... was driving 4 Hrs... 2000RMP... LTFT - 7,8 (yep minus 7,8) ... the faster i drove... the lower it went... had -10,4 when driving at 3800 RMP. coasting of course put all trims to 0 in 3 sec... Havent found other data showing fuel trims which makes sense.. have 2 other fuel trim data but those are stuck at 32% all the time... and this car has 2 sensors only ( 2004 ford 4cyl. Mondeo 1.8 petrol )

Its an exhaust leak

you will have to show me where a computer does a diagnosis for you. I never heard of that in my life. What computer actually does the diagnosis as opposed to just providing data that has to be skillfully interpreted? I would definitely buy one of those computers for sure!!!! Please tell me which one does that! Also where will that take me? What places can I go as a result that I am not already at?

@@SchrodingersBox the interpretation is the easy part.. the computer gives you all the answers to questions you are searching.. your criticism serves no purpose to a room full of empty seats

I've had to replace two yellow sticker ETM's and finally bought a pre-programmed Xemodex which is contactless and no problems since. The old throttle cable and a tension spring worked so well by Volvo needed to be leading ede, I guess.

That is a great solution. But buying the contactless tps yourself and cleaning the throttle body is a longterm fix also at a much more cost effective way