C70 S70 V70: hesitation issue not fixed!

[fulham75]

I left a post here a couple of days ago regarding hesitation on my 1998 v70 2.5 T. auto,the car drives fine while your pushing the throttle ,but if you back of and try to cruise at a steady speed ,it seems to pull back,and hesitate ,hit the gas slightly and its fine.i plugged my cheapy obd in and got codes p1174 and p1171,i should ad that I cleared the codes then drove it, as soon as it reached operating temp the missing started ,but the engine light did not come on,which it was on all the time before,i cleared the codes,and ran it down to a mates garage ,and told him the codes ,he plugged his hand held all singing and dancing obd in ,and the only fault that came back was p0137,oxygen sensor 2,,so we changed it but the problem still remains ,ive taken out the throttle body and cleaned it although it was pretty clean anyway,ive checked for air leaks,ive cleaned the maf still no joy .I have read here it could be the maf going bad ,but would a maf problem be more likely if you were putting the car under load ,,rather than takIng the load off?,and wouldn't the engine management light come on?what I find strange is the engine light is going out after start up,and not coming back on again like it did before when the hesitation starts!,ive only just got the car ,and sods law no probs at all on the test drive ,and drove it for a good 15 minutes .i plugged the car into my cheapy obd tonight and code p1174 is showing but not 1171 ,yet on my mates obd ,only p0137 showed!.i know its a long shot but im wondering if maybe its the fuel filter ? the car idles fine so don't think its the etm ,had that on my c70,and that caused rough idle and loss of power.i was thinking of taking the maff out of the c70 ,its a 2 litre lpt,and trying it in the v70,just to see if there was a change ,but am worried it might bugger it up as they are obviously different,sorry for such a long post but I really want to sort this any thoughts or ideas,most appreciated oh forgot to add if I rev it in neutral it seems to splutter around 4000 rpm,clears then splutters ,don't know if this is relevant cheers steve

[fulham75]

forgot to add I unplugged the maf and drove it made no difference to the problem,didnt even bring engine light on

[capt jack]

Sorry you've not got this sorted.

I'd go back to the original thread - spark plugs.

Over a combined ownership of nearly 20 years and 320,000 miles, I can say for absolute certain that both my old V70 and SWMBO's current S70 have developed odd hesitations and misfires as the plugs have faded.

Just last week SWMBO mentioned that her car 'felt funny', and a quick run up the road confirmed a slight hesitation at around 2000rpm. I took the plugs out and found the gaps to be a tad over .8mm. I put them in maybe 2 years (15,000 miles) ago. Re-gapped to .7m and things were hugely improved. When I could get to the motor factor I got some new plugs, and the car is now back up to scratch again.

When I had my V70, admittedly it was on LPG, but if I didn't fit new plugs every 10,000 miles then sure as eggs are eggs, I'd get hesitation and misfire. I know that LPG tends to exploit ignition gremlins more than petrol, but on LPG I've known some plugs (Bosch Super-Plus) last no more than 3000 miles.

At the very least it'd be worth whipping out the plugs and checking the gaps. The overall condition of the plugs will give a clue as to the state of the engine generally.

A new set from Eurocarparts or similar will be less than £15.

Cheers

Jack

[fulham75]

thanks I will check them,today after advice from a guy who works at a local garage ,I I sprayed a couple of cans of inlet cleaner in ,running at 2000 rpm ,while I sprayed at intervals ,then took it for a run giving it plenty ,no crap out the back as he suggested it might ,but for about 20 miles no issues at all, no hesitation ,either cruising or backing off the throttle as it had done before,feeling pleased with myself I headed home then bugger me dropped back to 60 mph ,the hesitation started actually worse than before , then the engine management light came on it was then jerking on acceleration as well.im really hoping its not the etm ,I had that on my 2000 c70 rag top ,had it repaired ,but I thought the issue with the etm was 99 to 2002,mine is 98.i did read a post on another forum where the guy had used none Volvo fuel filter and had this problem ,his garage then fitted genuine Volvo ,and problem solved,apparently not uncommon.its just a shot in the dark .If I cant sort it I have a auto electrics firm near by ,and im on good terms with the guy ,I might let him run through it ,before I start replacing this that and the other ,I did think maybe maf going bad but again shot in the dark,problem with fault codes is they don't always relate to the actual problem cheers steve

[Jp003]

Hi Buddy

I have the dreaded P1171 code on my C70 2.3T5 2001 and its a pig to find out what it is. I am at a similar stage you are with trying things.

1st thing to do is call FRF Volvo and ask them to run the code P1174 because i have no idea what that means and the only people who can tell you are Volvo or someone with vidas

P1 codes are manufacturer specific and most code reader just bring the code up but wont actually tell you whats wrong. On my reader P1171 says it is the accelerator throttle. I haven't tried cleaning this yet and Volvo don't say its related to P1171 so who knows. I running out of ideas on mine so ill give anything a go if it is cheap.

I have so far tried new TCV and cleaned MAF and intake and PTC valve, new turbo pipes, new fuel filter, new CAT.

If its giving P1171 then also check fuel pressure, could be a dirty injector, faulty thermostat or ECT switch

P1171 means long term fuel trim upper limit

Causes of upper limit

Intake Air leakage
Exhaust system air leakage
low fuel pressure
defective heated oxygen sensor (HO2S)

Causes of lower limit (dont know what code is)

Intake Air leakage
High fuel pressure
Leaking injectors
defective MAF sensor
Contaminated engine oil
Oil level too high
Defective heated oxygen sensor (HO2S)

I have just bought a cheap fuel gauge and vales etc to link up to my fuel rail to see what fuel pressure I have. Problem is the code could be something silly but most the time costs money trying new parts.

Have you done the PCV check to make sure your not blocked?

Good luck mate I'm pulling my hair out. Like i said put a CAT back on my car but its still over fueling and ive lost more performance, just waiting for the P1171 code to hit again as the long term upper limit is still going through the roof.

A real time data scanner will help you check the MAF and ECT sensor, O2 sensors, and ignition timing advance, and fuel mix. Its a cheap way to see if your MAF or sensors are faulty. My code reader was under £70 and does all of the above.

Have you had a remap on the car at all?

Hope some of this helps

JP

[fulham75]

no ,no mods just a standard 2.5 turbo,ive only had it a few days ,thought it ideal to do some load lugging for a while .I have taken mine to local auto electrics fella I know ,see if he can throw some light on it ,cause im wondering what to try next,im going to put on a new fuel filter ,because that is my hunch ,but of course it will not be as simple as that .when the etm was faulty on my c70,the idle was all over the show and power right down,not that the 2.00 lpt is much to right home about power wise ,so I have ruled this out.wish I had not got the bloody car now ,,,I don't mind if there is a glaring reason for a problem,but when it just drains the pocket getting nowhere ,it makes me want to go back to the older audis,,quickly going off Volvo lol

[Jp003]

Just out of interest. When you get the hesitation if you back off the accelerator and put it back on full does the power kick back in?

Also your spark plugs are worth a check like captain Jack said.

Coil packs can be a pain in the bum and cause hesitation and miss fire but doesn't normally throw up the codes you have.

Check with Volvo parts like at FRF and ask nicely and those boys will help you out and email you the breakdown of the codes. At least that way you might have half a chance of working out what it is without spending a fortune.

Like I said I get the P1171 code but haven't had the p1174 code you mentioned.

Just out of interest what O2 sensor did you use to replace the old one? Genuine part or a cheap miss match off the Internet? I tried the cheap option first and the sensor didn't work properly! Had to do some homework and replaced with correct Bosch sensor using the Bosch website.

Hate to say it but it is very easy to throw money at a Volvo trying to fix them when they start to go wrong. That's why a Real time data scanner will save you money. No point reading stuff when it's working correctly.

Most the time I find it could be one of ten parts gone wrong and it doesn't throw an engine light!!

Good news is there are some real good guys on this site who will help and save you time and money. Just keep asking and you will get help.

Regards

JP

[B00TS]

In addition to what everyone else has said:

Long term upper fuel limit (breached?) sounds to me, when translated from software engineer speak, that the ecu considers it is having to regularly deliver more fuel than it should have to, to keep combustion stoichiometric. i.e. roughly 14:1 air to fuel.

This could be because the lambda sensor is giving it duff readings about the exhaust gas composition but just as likely is that there is air getting in somewhere between the MAF and the cylinder head.

When air gets in somewhere after the MAF, it is 'un-metered' air that the ECU doesn't 'know' about thus the engine, without closed loop feedback, would tend to run with too lean a mixture.

If the lambda sensor is ok, this lean mixture is detected by the ecu and fuel delivery is increased to richen the mixture up. It is most likely that this over-delivery is what the ecu is reporting with the fault code.

I would check really carefully for cracks or splits in any of the induction pipework post MAF and in any vacuum hoses connected to the inlet manifold. Also check the inlet manifold gasket and the crank case breather system.

The smallest splits or cracks in any of these could give the symptoms you report - particularly the irregularity of them. The symptoms will come and go as the leaked air volume varies with flexing of the damaged pipe.

Many moons ago I spent weeks and £££ trying to stop absolutely lousy running on a Bosch K-Jetronic engine. Turned out to be some stupid 50p rubber O-rings not sealing the injectors into the manifold and letting random amounts of air in after the 'meter'.

Hope this helps...

Boots.

[B00TS]

Thinking some more on this:

Restricted fuel supply or low pressure from the pump could also give the same code.

The ecu sees a lean result from the lambda sensor and tries to deliver more fuel to correct but due to the restricted supply ends up with the 'tap' fully open but still doesn't get the correct result in the exhaust gases.

Would be worth checking the fuel filter is not gunked up and no kinking of fuel lines...

[Lmason]

have you considered the air barmoter sensor ? located behind offside headlight