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Hi, I just bought a 2000 chevy tracker 2.0
On my way home I put the pedel to the metal and rpm went up but not past 4-5k with no noticeable acceleration.
Got home and started poking around.
What I know. Cold or warm, driving or park
This wot rpm "bog?" Happens. Cold it will be around 3-4k rpm, hot around 5k. Now if I do say 80% throttle the rpm max out easly.
Idle -warm is around 750 rpm.
Their is a slight quick hesitation/stutter when I blip throttle from idle.
I do have a vacuum leak code. (Tried quick search and water so far)
And there was a crank sensor code that i cleared before 40 min drive home.
My highest tech tool is a code reader with live data.
Was told engine has been replaced awhile back.
So do you smart feelers have hints tips tricks I can digest.
The symptoms don't really fit a vacuum leak but they do fit a dirty MAF.
You want to look at live data for the short and long term fuel trims and how they are changing from idle to high rpm. If the fuel trims look fairly normal at idle but add fuel at higher RPM then it could point to a MAF issue.
If this engine has a Schrader valve on the fuel rail so I would also want to go after fuel pressure measurements as a restriction on the flow of fuel would cause similar symptoms.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Last edit: 8 years 4 months ago by Andy.MacFadyen.
Thanks for the replys.
I did the best I could with live data, im not completely sure if any of these are fluctuating while driving. I may do the tests agian with assistance.
Engine off key on.
Ect 77
Stft b1% 0
Ltft b1 2.3
Map(InHg) 29.2
Spark adv 5
IAT 77
MAF ib/min 0
02 S1 (v) .085
02 S2. 99.2
I'm assuming the Maf data is in lbs/min and not gr/s correct?
If so looks like the engine is breathing ok.
The o2 sensor is your clue in the data. You are running lean at WOT. You need to get a fuel pressure gauge and see what the pressure is at WOT. I'm guessing that the pressure will drop very low under load.
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The following user(s) said Thank You: Tyler, Dothedew92
Correct Ib/min.
Thank you, I will do some fuel test.
I've been watching Pauls videos for awhile, I'm still wrapping my head around data. I'll get there, expecially with hands on and guidance.
Ok guys and future readers this is what I've done. I rented a fuel pressure tester. After fighting with the fuel filter I ran into some problems.
The steel fuel line cracked near the filter, so I cut the short bad part off with tube cutter. Put in a fuel hose from there to NEW filter (old was really dirty). Found out the rented tester was broken..
Just the new filter, and possibly cutting off bad line (unless it started leaking when I began pulling on things) has fixed my symptoms.
Went and bought my own pressure tester to make sure all was well.
Now just priming key engine off My psi jump to 50-60 (I think this is high? ) then leaks down real quick.
Car at idle psi is 35. Wot jumps up to 40 psi
No visible fuel leaks. I pinched the fuel hose (not vacuum ) off at pressure regulator engine off priming key psi jump up to 70(high?) leaks down to 60 then stays there.
I then started the car with pressure regulator still pinched off. NOT SURE IF THIS IS WISE as pressure is real high I think.
Car running, pressure regulator pinched off my psi is flicking between 70-80.
Shut car off, unpinched regulator hose.
Retested engine off priming key. Psi goes to 40 and stays. No more leak down. ..? Lol
When pinching off the return line on the fuel system you can expect the fuel pressure almost double. That is normal. You shouldn't run it for very long doing this.
I suspect the original problem may have be a choked filter restricting the fuel flow, hence elevated fuel trims at higher fuel demands. It may be the pressure leak down could well have been made to look worse by air still in the system after the filter change.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Andy.MacFadyen wrote: I suspect the original problem may have be a choked filter restricting the fuel flow, hence elevated fuel trims at higher fuel demands. It may be the pressure leak down could well have been made to look worse by air still in the system after the filter change.
Hopefully that's it. I was thinking maybe the return line was the kind that is a hard plastic line inside a rubber tube, and is now perhaps kinked.
Purely speculative of course, I'm not sure what the fuel lines are made of on a Tracker of the top of my head.
I'm glad to hear that it's back in action!
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