Check out my sparkplug... (p1128 1130 related)

Hi there! I'm in the procces of fighting p1128+1130 along with -20% LongTerm fuel trims and VERY loooong startup times. Replaced the AOS yestearday but, opened the old one - membrane looked to be in perfect shape Even tough there was some oil presence in the intake ducts, so I keep hope that old AOS was somehow bad. Have not restarted the car yet as I have to put all the hardware back. Maybe while still there, I will check my fuel pressure. I took one of sparkplugs out , check it out : Looks like OEM ones, the most expensive ones. Seems ok to me, what you guys think?

The plug looks ok to me. What year and model is your car?

2001 3.4 C2

2001 uses DME 5.2 so P1128 and P1130 indicate both banks are too lean when close to full load . I would check the MAF (voltage reading using Durametric/OBDII scanner/multimeter) and the fuel pressure. If you have an external fuel filter under the car, it's also a good idea to replace that.

Checking voltage would be a good idea., but...I already tried clearing all codes, disconnecting the MAF and driving like this for my daily commute. At first, the car started "easily", but after a lengthy drive, startups were the same like before, loooong, and in the end P1128 came back. So I kind of dicarded the MAF possibility for now. Will try to do a fuel pressure test. Any specs, write ups on that besides that I need angular Shrader fitting?

Definitely check the fuel pressure then. Specs are here: Stationary engine 3.8 +/- 0.2 bar Engine idling 3.3 +/- 0.2 bar Quantity supplied must be at least 850 cc/30 s,

my 1128 & 1130 codes went away with a new MAF

Little update, Got new AOS in place, and cleaned MAF which seemed perfectly clean in first place. Drove for the weekend, around 100km in two days - CEL has not come up yet, even though Long Term Fuel trims are again at -20% and -19% so I suppose it's mater of days for it to come up. Startups are somewhat improved but barely, probably due to new starter I put in, which cranks faster, but on hot engine, I still have to crank for 5 seconds and more. I took MAF reading in lbs per minute. I got 1lb/min at idle, and 2.9lb/min at 3000rpm no load. Anybody can confirm these readings as normal? Thanks!

Your problem is either the idle air motor or the fuel vapour purgd solenoid/valve near the throttle body. If this valve is stuck open, it will make starting the engine take 5-10 second. I had this problem and after I cleaned the valve out the engine started like it should. Remove the valve and then active it with a 9V battery. If you can blow through it with your mouth when the voltage is and isn't applied to the valve then it's either gummed up or siezed. You can try leaning it out with some brake cleaner and cycling the valve with the 9V. At some point it should start clicking and when the click start to sound like metal on metal, the valve is clean.

The MAF should read ~4.2g/s for your car at idle, fully warmed up and no load. That's ~0.55lb/min. Your MAF reading is twice of that so that explains the -20% fuel trim to cut fuel. BTW, I take that you reset the DME after the AOS change (so fuel trims were reset too)?

@Imo - thanks very much, I'll try that one. @Ahsai - thanks to you too, DME was cleared, battery was disconnected for few days. So my MAF is out of whack then? I saw MAFs on eBay going for around 30$, any experience with them?

Is your intake stock? Is your rpm at idle close to 680 at no load when the MAF read 1 lb/min? I checked the spec for a 3.4, at idle it's 15kg/hr which is ~4.2g/s, which is 0.55lb/min. Cheap MAF from ebay is most likely no good. The other way to check is if you unplug the MAF, reset the DME and see if your fuel trims come back to normal. If it does, it's highly likely your MAF.

Don't just keep throwing parts at it or it will get really expensive really fast.

My intake is stock. I already rode around with MAF unplugged, got PSM, ABS, CEL lights right on. And by the end of the day, same p1128 came back, so I kind of discarded the bad MAF idea and plugged it back. I think the trims went to around -20 too, but can't be sure on that. My idle is more of 800-900, but have to double check on that too.

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Agree on that. BTW, I sent you a PM regarding that Idle purge vapour valve.

If idle is 800-900, it's possible your MAF reading of 1lb/min is OK. The Porsche spec I gave requires @680 rpm. Imre has a good point on that purge valve leaking as that will definitely create an internal air leak.

Update : just checked the "air vavle" per Imo insructions - mine worked perfectly Did a voltage probing on the MAF with ingition ON = 1.1V and with car running = 1.7V at idle 900rpm. Manual states 1.4v = my MAF is really out of whack??! Or is my idle too high at 900? manual does not specify at which idle speed 1.4V comes.

Idle way too high. Spec is 680 +/-200rpm fully warmed up no load if memory serves. 900 is another indication of air leak after MAF. 1.7v at 900 sounds ok to me. Have you checked the usual suspect - oil filler tube for air leak? Any suction if you try to remove the oil cap when engine is idling?

If your A/C is on it will bump your idle above 680

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No pic is showing...

Fixed the Picture link (just figured Google Photos would show to some but not to others)

Update : Start it up this morning and played with Oil Cap, taking it on and off - there seem to be a good ammount of vacuum present in the crankcase, engine would start shaking, almost missfiring with the cap off. so the AOS is brand new - where else can vacuum be pulled into the crankcase?

Check the idle air controller, they gum up too. It's bolted the the side of the throttle body. If it's stuck a bit open, the idle will go up.

Imo - I will! To reformulate my earlier question - is vacuum presence in the crankcase normal or not? And If I'm to do an air leak test with some sort of smoke machine (or cigar) - should I expect smoke from oil cap or not? Pelican says there should be steady smoke from oil filler tube, which sort of answers my question already - vacuum in crankcase IS normal...or not?

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His is a 2001 so it should be electronic throttle -> no idle air controller.

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A slight vacuum (at around 4" water of suction) is normal.

I think I found the problem...will give full update tomorow, after a test drive

The suspense...

No, seriously, found a vacuum leak by pressurizing manifold with what I had at hand. Just don't want to shout out loud that the problem is solved unless I drive around a bit.

What is that hose that you pump air into? I don't recall such air hose there. The elbow in the last photo has an o-ring inside that can harden and leak (around the grey clip). Is it where it's leaking from? Btw, I like how you inverted the rubber intake sleeve to seal the throttle body. Very creative

First test drive Update : The thing STARTS just like it should!!! Can't wait to take Long Fuel Trim reading too see it go to normal. "What is that hose that you pump air into? I don't recall such air hose there." It's a hose that goes from Air Valve to Throttle Body

Update : Fuel trims are out of specs again, reading -20% on each bank and startups are long. No CEL yet though. And idle is around 960 with AC off Took fuel pressure test with two different gauges and imagine what - 75 psi! Disconecting vacuum line from Pressure Regulator does nothing, vacuum is good -18inch After posting here, kind folks pointed me to spec which should be 55psi. Next step would be to retest the FP with return line disconnected see if it's not clogged somehow - I don't feel lile replacing another part without being 100% certain that it is the problem.

SOLVED Clogged return fuel line

Nice work. So the fuel pressure was actually too high and the negative 20% fuel trims indicated that. It's interesting that 1128 and 1130 (too lean at idle) point to the opposite. I guess it makes sense as the DME reduces fuel under driving so it has to add fuel at idle.

I'm not 100% sure that theese codes mean we are lean. Aren't they more about "adaptation limit reached", meaning that we either went too lean or too rich? I'll be hooking up a scanner tonight just to ascertain that the trims are back to normal. But so far, start ups are just perfect and this makes me happy after two months of hunting.

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1128/1130 mean lean for DME 5.2. For DME 7.2 and on, they mean either lean or rich. Yours is 2001 so it should be 5.2 http://www.renntech.org/forums/topic...30/?hl=seeking Anyway, I'm pretty sure you've found the culprit.

so I guess the question is.... how the hell did that fuel line get clogged like that!?@? Were you not running a fuel filter?

Where is that fitting that you removed located? Maybe I should check mine if its easy to get to.

Clogged return line??? How? If the return is clogged, some of that had to go through the injector strainers/filters too. I would pull the injectors, pull the strainers and have a good look at them. They should also be clogged.

See Figure 4 on this page http://www.pelicanparts.com/techarti...eplacement.htm So the fuel trims are finally normal, -5% on both banks so that's good. Cold startsup are perfect but....heat soaked restart after few minutes are as long as they used to be. When I did the fuel pressure test, I noted that the residual pressure was droping almost instantly after the pump was shot, not a good sign. How it got clogged? I wish I knew. I got very little history on this 2001 C2 and all I know that it was barely driven in the last 6 years. I guess this is how it go clogged?! Totally agree, as I need to diagnose that residual pressure drop. What are the strainers btw?

They are small mesh filters at the inlet of the injector. It drops into the injector body.

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My guess is the fuel filter bursted at some point. Good call checking the injectors.