Hey everyone, today I ran my car at the UAS dyno day. It made 286.7 rwkw at 4,200 rpm but was running severely lean and pinging badly. I was lulled into a false sense of security when I got the car because the coil packs weren't doing their job and it was blowing black smoke out the back, so I thought it was rich, plus I had it checked on datascan/ecu talk or whatever you call it and it seemed fine. I put new coil packs in it yesterday and it fixed a big flat spot up, but after I changed coil packs, I got a BIG stumble/miss at idle. I'm putting it down to coincidence, because I didn't touch anything else, but who knows...? Anyway, tomorrow I intend to pull the car apart and work through it until I find the issue, then I'll get it tuned to make the power it should have. Any suggestions on where to start? I intend on checking all hoses and clamps in the engine bay (even though I thought if they were blown/popped off before the manifold, they'd make the car run richer?) Is there a way to test my fuel pump with a multimeter? - I have been advised that it probably isn't the fuel pump as it's lean across the board, but I just want to cover the possibility anyway. I'll pull the fuel filter off and see if it's blocked. Procky plugged his ECU talk into the zed and apparently the AFM seems fine.... Other than that, I'm out of ideas. Is there anything else you guys can think of that I can physically check that would cause a car to run lean? Once I go through everything I'll hand it over to be put back on the dyno and tuned, but would rather not spend money I don't have getting people to find faults. Any help is greatly appreciated, fairly frustrated at the moment. Aside from that, thanks to everyone who attended, it was a great day, so many nice cars and people!
How long is a piece of string?? Do you have the dyno printout showing AFR's? Could just be the tune is poor, or fuel pump is on the way out, or the injectors need a clean or the fuel filter is old and clogged.
Fuel filter could well be clogged. Recently the fuel lines split and I found the lines had rotted from the inside out over a period of time. AFR's were all over the place, up to 17 at the start of the run and when it's flat it was around 13 iirc. Will get the dyno sheet out of the car later. Is there any snake oil on the market that will actually clean injectors safely, or is it a plenum pull just to get them cleaned and tested?
Redline injector cleaner is great but those injectors are just about new. I'd be looking at pump and filter
If you don't know when it was last changed, definitely change the filter. Cheap and easy to do. Then it really needs to go on a dyno and check the tune in the ecu. And/Or install your own wideband sensor and guage.
Yeah, I'd like to eliminate any physical issue before sticking it on the dyno and checking the tune, just a bit of a waste of money if I strap it down and the fuel pump/afm/vacc lines/pressure reg/anything else on the car is bad. When it was on the dyno today and Dave was loading it up, the gauge on the FPR went up to 5 sorta early on, and no matter how much more the revs climbed, it wouldn't go above 5. Dave said it was OK because at idle it's like 2.5 and if it's going up to 5 it indicates no issue, but idk. Seems to me like it should keep going up with revs? Will get proper measurements off the FPR gauge in the morning, I know "5" doesn't say much, lol.
Cheers Nem! Anyone know if this is enough fuel pressure? GT28RS turbos, 555cc injectors, turbos set to 21psi, don't think it saw 21 on the dyno, but not sure because boost wasn't on the graph, just AFR and power.
OK, so I have adequate fuel pressure.... Still possibly leaning out due to a blocked filter, the pressure is there, the volume isn't? Or is that not possible?
Is the guage on the reg? If it is and you're seeing 5 bar pressure your fuel system isn't the issue, you're getting fuel. The problem is your tune. The tune isn't letting enough fuel through the injectors. What ecu do you have? Nistune?
Been looking on youtube and on the net for ages. Can't find any how to's on testing to see if a pump is weak (can only find tests to see if the pump works or doesn't work, lol). Probably impossible given the fact I'd need to test it under load.... Any suggestions?
Yeah, Nistune. Tune can't be that bad, something has to have gone wrong with the car... This is what it made on the same tune on the same dyno with the previous owner. This is a run from today (it made 286 when fixed a vac leak from the plenum to the pressure reg).
Just went out to the car to get the sheet and also have a look at the pressure reg. Nem's right, 72psi, so there's nothing wrong with my pump obviously. Here's one of the runs it made today with the AFR's on there. On the last run of the day, the AFR's started out in the 17 range.
The 340kw graph, do you have one with afr also? You really need to compare with afr & boost side by side to make sense of those graphs, but from 4500rpm in the last graph 12.5 is fine. Before that isn't lol. Maybe you've got an injector playing up, or the filter has let some junk through that causing a blockage somewhere, or something's going awal with your ecu. Put a new filter in, run a couple of tanks of United Premium 100 through it, then change the filter again. If you're concerned about the ethanol do the injector wiring fix. The 10% ethanol will clean any junk out of your lines.
Looking at that printoff something is quite wrong... Go through it with a fine tooth comb making sure there are no boost leaks at all, all connectors are clean and tight, base timing is spot on, TPS spot on. If you are maintaining correct fuel pressure then the pump is not the issue. As Shane said, possibly something blocking up an injector. Have you pulled the plugs to see if there is any variation between the cylinders? If you have done all that and still no go, then tune/ecu related.
^^ That pretty much covers it I think. Only thing though, if there's a boost leak, wouldn't that cause it to run rich?
