jcorallo

Your test is invalid because you're not keeping an important parameter constant between the two tests: speed. If you use the brakes to hold yourself to the same speed coasting as would be provided by engine braking alone, your fuel mileage will be better using the engine braking. The engine should use essentially zero fuel under engine braking conditions. I've yet to see a fuel injected car that fires the injectors in an engine-braking scenario (assuming the revs are above idle). The injectors are absolutely firing if the car is at idle or the idle circuit is engaged (< 1300 RPM or so). J I'll chime back in now. Looks like I got you all thinking! So it wasnt a daft Q after all... John V, I had a suspicion that the fuel injectors DO fire when the engine is on the over-run - I thought it was possibly to keep the top end / valves lubricated and also possibly to keep the catalytic converter up to temp ?? I think the above test by Michael just about proves this theory since the MPG reading on the OBC is directly linked to the pulse width of the injectors from the DME. Jules

....when going DOWN HILL : 1) Staying in gear using engine braking - or 2) Shifting into neutral and letting the engine idle, using foot-brake to control speed DISCUSS! B) Jules

yes, but how.

Thanks Tool Pants, that really helps. Its hard to tell, but it does look like the cams are sitting slightly out of their journals at the far end, but I guess that is to be expected given how they are held in. At least it seems the cams wouldnt just flop out if the cam cover was removed, with the engine still in place in the car. Regarding the VarioCam solenoids - do these just operate an oil pressure control valve? Or is it the solenoids themselves that move the cams? Jules

Hi, Has anyone got any pictures of the Boxster 2.5 engine with the cam-cover removed, and maybe a picture of inside the cam cover? A picture tells a thousand words and all that - I cannot tell from the workshop manuals if its the cam cover that holds the camshafts in place, or if the camshafts are bolted to the head with saddles. I wanted to know if you removed the cam covers, if the cams would just flop out... and if I needed a special tool to hold the cams in place when removing/installing the cam cover. Jules

OK thanks - that confirms it. 1) DME 2) Alarm unit 3) Key heads (with the immobilidsor pill) and key remote controls Presumably, if I was to install the donor DME and alarm unit in to my car, and in the end decided to keep them installed permanent, I could get an OPC to reflash this donor DME with my correct VIN and immobilizor codes, and I would then use my original key fob / remote control ? Do I need to know details of the original car the DME came from, in order to re-flash it? Jules

Hi, I wanted to try a replacement DME in my Boxter 1997 2.5 5sp manual (RoW - UK version) Dont want to go into why in this thread... I just want to know what I need to do to accomplish this for a quick test I wanted to do. So apart from the DME unit itself, what other control boxes from the donor vehicle do I need to bring over for it all to work, and where abouts in the vehicle are the particular units located? I dont want to have to bother with re-programming the donor DME with immobilisor codes etc, I just want to try a different DME, and can bring over the other control boxes as needed for it all to work with no programming... So what do I need to make a working system? Cheers, Jules

Answer: Just pull it as hard as you can and it will come out - there is enough 'give' in the air box, and enough 'spring' in the clip for it to force out rearwards towards the back of the car. I guess it was installed this way during assembly since it was easier for an operative to insert in that way on a production line. In terms of getting it back in, you wont be able to get it back the way it came out unless you use a lot of force with the risk of breaking something. You have to put the clip back in from the engine side, with the closed end facing the engine and the open end facing the airbox. Hope this information will be of use to someone one day..! Jules

Hi, Boxster 1997 UK 2.5L. How do you remove the Fuel Pressure Regulator (FPR) on the 2.5 Boxster? I tried to pull out the FPR retaining clip but it hits the air cleaner box. Cheers, Jules

I normally remove the CV joints from the shafts to replace boots, but I'm aware that tools and techniques exist that stretch the rubber boot over the CV joint, without having to remove the CV joint from the shaft (joint still has to be undone from the transmission though.. Heres one: http://www.bootslider.com/ Also, there are various "cone" sliders about that allow the boot to slide up the cone, over the CV joint and onto the shaft. Jules

What year and engine is the car? How many miles? Could be a worn engine / valve guides.... but: 1) Check you havent overfilled the engine oil. 2) Next thing to suspect is the AOS - air oil separator. Have a look inside the throttle housing and see how much oil is coming through... Cheers, Jules

As mentioned above, the front rads on these cars collect leaves which rot leading to leaks. If you are worried about over-pressure, yes check the coolant cap, but also get the air in the coolant header tank 'sniffed' to test for cylinder head gasket leaks (after the engine has been run for a bit). On my old VW Golf VR6, the heater matrix deep in the dash blew apart (fun - not) because the head gasket had gone and was forcing combustion pressure into the cooling circuit. Jules

Hi Loren, No fault codes, I have the dumb early UK DME which is not fully OBD2 compliant, and I cleaned the throttle a while back in Feb - even then, there was nothing much to speak of to remove - all very clean. At weekend I lubricated the IACV with some WD40 and the car has been running really well last couple of days now - so I strongly suspect a problem with this valve. The engine pulls cleanly and also I don't get the erratic bouncing-back-to-idle at junctions - just smooth now. Its a bit irritating that I havent found something definitive, but its very coincidental that after lubricating the IACV, the car runs so well now... Cheers, Jules

Hi Loren, Yes, when I come to a junction and dip the clutch, the revs sometimes shoot way up past normal idle speed, then down to a shudder before recovering back up to idle. Also my car very nearly failed the emissions test. I have new MAF, O2, plugs - which all work - shouldnt be running bad. With regard to my 2nd question, I meant with the IACV disconnected from the car - my flap is slightly open so was wondering if this was normal? My IACV was buzzing which was what made me look at it. It was making a rattling / jingling / gurgling / humming sound. It made each one of these sounds over a period of a minute!! Cheers, Jules

Hi, Three things: 1) I have access to a PST2 and was testing my IACV which I suspected to be faulty. I removed the IACV from the throttle body, but left it attached to the wiring harness and left the unit on top of the oil cooler, angled so that I could see the flap. When activating the IACV test in DME Drive Links, the IACV snaps open and closed very quickly about once a second. I'm wondering if this is normal - I was expecting to see the flap move slowly open and slowly closed, not snap open and shut as fast as it could. Or does this behavior mean the IACV is sticking? 2) Also can someone confirm, that the IACV flap is normally slightly open - maybe about 1/8 inch (~3mm) - at rest? 3) With the ignition on, engine stopped and the IACV connected up as normal, my IACV rattles and hums and gurgles. When I removed the IACV and shook it, it sounded loose inside. Does this mean its worn out? Cheers, Jules

996? I have a 986! I dont recall seeing a DME Tests section - but I'll have a look tonight. Cheers, Jules You posted in the 996 forum. Just go to the 986 section - it has the same test. ahh- :oops: - thanks I'll look tonight! Cheers, Jules

996? I have a 986! I dont recall seeing a DME Tests section - but I'll have a look tonight. Cheers, Jules

Hi Loren, I have access to a PST2 now - where do I find the above status check screen? Cheers, Jules

ABS bleeding is not supported on Durametric as yet... unless you have a secret Beta version, Loren??!

insite, tholyoak and Richard Hamilton - thanks very much for your help and suggestions - really much appreciated! :thumbup: :beer: I can actually start enjoying the car now - its been like this since I bought it at New Year....! But I've been steadily working through the list of things to do on it - previous owner loved to clean and polish the car, and it has full service history, but thats about it - I dont think he knew it wasnt running right... There are a couple more things to work on yet - but I'll start a new thread for those....! Jules

OK guys the problem is now solved! Yesterday I decided to strip off all the intake piping and throttle body and check for leaks. I found two significant problems and one minor problem: 1) One of the large hose clamps that secures the rubber sleeve to the intake distributor seemed to come undone a bit too easily. I never did check these for tightness... The suspect one was on the left side of the engine serving cyls 3,4 and 5. 2) The idle air control valve, although looked very clean and dry and not gummed with oil, was "crunchy" when I pushed the swing door back with a small screwdriver. There was a layer of carbon causing it to bind slightly. Once cleaned off, the door moved very freely. 3) There was a slight "plug" of thick oil in the signal line to the Fuel Pressure Regulator which I blew out. I also cleaned the throttle body out completely and removed a very thin layer of oil from the inside. I also hoovered out the air filter sponge and cleaned and de-greased all parts before reassembly. Once back together, I reset the DME and the difference was superb. Rock solid idle, no cut out at 1400rpm and part throttle is as smooth as anything. No more surging or hesitation. Transition from idle to any rpm and back is now as you would expect - flawless. Regarding point 1) above. When I'd put the intake back together and started the engine up, viewing the running engine from the drivers seat (I had both access panels removed) I noticed how much the plastic intake manifolds (intake distributors) moved relative to each other at different levels of throttle due to the vacuum inside. I actually measured it! At idle, the two intake manifolds are a good 2mm closer together. Open the throttle and let air in quickly, and they "relax" outwards. You can also see the flat top section (that says Porsche on) collapses in a couple of millimeters at idle, and springs out when you open the throttle. Given that these manifolds move about so much, you can see a loose clamp would cause havoc - item 11 in the pic below (the one that was loose on mine was the 2nd one in, going left to right)... Cheers, Jules

Yes the AOS was the first thing I looked at as I did a lot of research before posting. Since I could not get close to the AOS, I pushed my digital camera up towards it and took a load of pics to view at leisure on my 21inch screen. The bellows really looked OK, but granted I can only see half of them.... AOS1 AOS2 AOS3 There is a very light misting of oil below the AOS bellows, but none on the bellows themselves - so I had discounted this as being the problem? I would assume that if the bellows were leaking, there would be oil actually ON the bellows? I could just bite the bullet and change the whole AOS system and pipes - but thats not cheap considering it doesnt look to be the problem? Jules

Yes gearbox is 5sp manual. oh - and another thing: when coming off decel back onto the throttle, its not always smooth - sometime giving a little jolt. Jules

well that certainly makes things a bit more complicated! can you describe the throttle hesitation bit as best you can? does it happen from a stop? from any constant speed to acceleration? on decel? this is a manual trans, correct? hi insite. Symptoms are as follows and totally repeatable: From cold, either when left overnight, or on carpark at my workplace: start engine let it idle and settle by itself. Whilst in neutral, very slowly increase revs towards 1400rpm. As soon as revs touch around 1400rpm engine totally cuts like I turned the ignition off and revs drop to around 600rpm for a brief moment, then revs regain back to around 1300rpm/1400rpm - all this happens in less than one second. Now trying this again for a second time, since engine has been running for about 30seconds at this point, each time engine is pushed slowly to 1400rpm, as soon as it hits around 1400rpm, the revs drop to 1300rpm. Now holding it at this RPM the car shakes like its mis-firing and the engine jumps about a bit and sounds like its struggling. When fully warmed up - the only symptoms are a feeling of surging at lower speeds and part throttle. Say when going along in 4th or even 5th gear at 30mph, you can feel the car hesitating. Its very uncomfortable and annoying. It feels like a misfire. The only thing I know about that RPM's, is that the VarioCams switch around then. So I think the VarioCam switching is possibly adding to the affect and making it more noticeable perhaps? Just thinking out loud here... I've not checked the fuel pressure yet - once I've ruled out any leaks I'll look into this. Cheers, Jules

Hi insite, Yep will do - thanks for the pointers. I suppose it could be a clogged air filter, but will check for leaks as you suggested. Also note that since this is a 1997 RoW model, there is no secondary air injection. It also very rarely throws a code since its pre-OBD2 compliant. It certainly does not throw a code as its running now. Cheers, Jules