Got a suzuki vitara g16b under load about 2500 -3000 rpm feels like its running out of petrol. also intermittent idling fault I have replaced spark plugs old ones worn below ceramic. New o2 sensor old one was only switching once every 10 seconds as opposed to 8 x a sec. replaced fuel filter. Fuel pressure and flow are within spec. I have checked the cts at various temps that is ok. I have put a scope on the coils all ok. good trigger voltage cannot scope the secondary. I have put my scope on tps ok nice and smooth. Checked injection duty cycle 3 ms at idle 19ms high rpm which seems ok. Checked airflow voltage within spec 1.9v at idle smooth to wot. Checked steeper coils and signal from computer all switching and working checked for air leaks. None that I can find. checked timing 6btdc with diagnostic bridged. Put my scope on the 5v rail from ecu constant and clean removed and inspected computer visually ok. Now I am stumped not often a car gets the better of me especially such a simple engine.Oh I have compression tested and checked operating temp and themostat as well. Problem is intermitent. I cuurently have throttle body off. Any ideas cause I not got any obviousley I have overlooked or missed something.
NZTools,
Aug 30, 7:29pm
Go back to basics. Get it to the point where it feels like it is running out of fuel, hit the clutch and turn the key off, then check the plugs. If it is leaning out the plugs will tell the story. Those are shockers for stuffed plug leads, and if the plugs were that worn the leads will be toast.
What about exhaust! is it blocked!
berg,
Aug 30, 7:34pm
Leads. Check the bakalite/plastic ends and look for a white spot or a burn hole. Very normal for these
NZTools,
Aug 30, 7:35pm
The pinholes are more often then not under the rubber boot at the bottom of the drop tube as well. Very hard to spot.
bigfatmat1,
Aug 30, 7:58pm
i have had a scope on the leads while fault is there there is still a good trigger voltage indicating spark is at the plug only. I have thought about the exhaust not checked it however. ill check that in morn.
dent,
Aug 30, 8:01pm
Can you raise the revs above 3000! dose it surg at 2500 revs! Dose it do it in neutral or only when driving the vehicle!
bigfatmat1,
Aug 30, 8:01pm
do these vehicles have any common faults like slogging keyways!
will visually check leads again i di nt pull rubbers off i do trust my scope but will leave no leaf unturned
bigfatmat1,
Aug 30, 8:03pm
only under load. not in neutral. yes you can redline it just sort of bogs down in that rev range does not miss or surge.
bigfatmat1,
Aug 30, 8:04pm
vrooooooommmm burrrrrrrrrrrrr vrooooooom is what it does
kingfisher21,
Aug 30, 8:10pm
Disconnect the EGR system if it still has it and try that, you'll need to block it off not simply disconnect the hoses, also check the primary part of the exhaust for collapsing internally, hard to tell, they are double walled.
therafter1,
Aug 30, 8:14pm
The fact that it is intermittent makes it that much harder. You think you have either isolated or solved the problem, and then it rears its ugly head again . lol
Nothing sucked up into the air intake system!
None of the air intake system located near high heat sources where the plastics can soften up and close up as the vacuum increases under load.
carmedic,
Aug 30, 9:37pm
Has it got any damage at the back! We had one that was cutting out under load, believe it or not it turned out to be the totally stupid factory routing of the power cables to the fuel pump. They are very vulnerable to damage (or in this case partial damage) in a very light rear accident. I realize you have checked pressure and flow so just a thought really.
budgel,
Aug 31, 9:55am
Blocked cat!
ceebee2,
Aug 31, 11:32am
They also have issues with the exhaust manifold melting on the inside and cooking engines.have replaced a few now.
thejazzpianoma,
Aug 31, 12:23pm
I havn't had the Suzuki but had almost exactly the same symptoms with another car once, intermittant idle miss and then issues up in the rev range. The fuel pump pumped up to pressure and had good flow when I undid the hose.
However, it was actually the in tank fuel pump all along, for whatever reason it would just play up once under pressure with the car running.
You however will have facilities to watch the pressure while the car is running (and faulting hopefully) which I didn't, that might of course give it away.Whereas I only gave it a quick check for pressure with a borrowed gauge and moved on to other things.
Might not be that but worth letting you know.
mrfxit,
Aug 31, 1:02pm
Possibly related also as Jazz suggested. Had the same sort of crud with a v6 Mitsi but variations. Started fine/ Fine revving while cold/ fine around town from cold, but as soon as you took it out of town 100kph etc &it got to a genuineFULL running temp, it would bog down/ stumble/ splutter/wouldn't rev etc etc
Mitsi dealers had it a few times/ diag's showed nothing even when the fault WAS present. Turned out to be the intank fuel pump overheating/stressing on high loads, despite testing ok No problems after that.
mrfxit,
Aug 31, 1:04pm
Those leads are a bit of a concern considering how far worn the plugs were worn down. (over stressed when hot maybe!)
petermcg,
Aug 31, 1:57pm
Yes I think they do, remove crankshaft pully and have a look, or check it against the flywheel marks if there are any.
bigfatmat1,
Aug 31, 2:33pm
substitutued plug leads and coils no change I can drive with fuel pressure flow meter on no change when fault occurs.
the-lada-dude,
Aug 31, 3:29pm
is a var val timing eng !is the comp getting bull dust messages, can you check ig timing whill driving or under loadswap the suzuki badge for a ford one ! are you holding your mouth at the right angle mmmmm. i think were getting close to nailing this problem
ozz1,
Aug 31, 3:42pm
wat year is this one matt! call me saturdayian.
jmma,
Aug 31, 3:52pm
OK, you're saturday ian (o:
the-lada-dude,
Aug 31, 3:57pm
No, me tarzanyou .
ozz1,
Aug 31, 4:02pm
very good. very quik. :). but matts only 700 yards away. so the "big fat" one can now. walk down the hill.:).unless he has moved!
dent,
Aug 31, 4:15pm
Must be suzuki time I just had one in for randomly cutting the injectors at 2500rpm then they would kick back in once the revs had dropped a little. Had a faulty tps. Sounds like possibly a different fault tho sorry.
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