many problems...what is this?

Rokee44 said:
hey. sorry, it wasnt my intention to disregard the suggestions I just didnt have a guage at the time and was simply asking if anyone knew of some other temporary things I could check while I was waiting for one, but I guess not. However mine was finally returned to me and I hooked it up and the pressure is dead on 49 psi at the fuel rail test port. I hooked it up so I could watch it while driving and when its acting up and no matter what it is constantly on 49 psi....so any ideas as to where im heading with this? kinda stumped as to what the next step would be. any help would be appreciated. thanks :)

- as a side note.... I replaced the O2 sensors as one seemed to have stripped wires and shorted out, and the upstream was in pretty bad shape... CEL is back on. going to go by a local shop and get them to read off the codes for me.
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Do you smell any fuel? Leaking injectors, or leaking o-rings that hold the injectors could also cause a lean condition.

I also wonder if in 98 the TPS was adjustable?
 
prettty sure the TPS is not adjustable in a 98. There is no smell of fuel for a little bit when I start it up but after a minute or 2 I get a lot thicker exhaust smoke and there is infact a little bit of a gas smell...but that occurs more around when the throttle is kicking up and sputtering...so it could be an overload from that...so I dont know if an injector leak would be my problem... might as well check though I guess? that vaccum thing in the first picture starts making louder-than-normal ticking noises sorta around the same time....
 
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Rokee44 said:
prettty sure the TPS is not adjustable in a 98. There is no smell of fuel for a little bit when I start it up but after a minute or 2 I get a lot thicker exhaust smoke and there is infact a little bit of a gas smell...but that occurs more around when the throttle is kicking up and sputtering...so it could be an overload from that...so I dont know if an injector leak would be my problem... might as well check though I guess? that vaccum thing in the first picture starts making louder-than-normal ticking noises sorta around the same time....
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Im more familiar with the RENIX era then anything else. Maybe someone else can help you better with that. I would replace the injector o-rings, and that "vacuum" thing that your talking about.. and then go from there.
 
hmm so we pulled an o2 sensor failure code...but its the same one we got before I replaced them. I looked a little closer into the fuel pressure situation.. although it stays at 49 psi..after you turn the engine off it immediatly starts declining..and over a period of 4 mins it gets right down to 10 psi. anyone know if this is normal for a 98 to do this? or should I take that as a sign that ive got a leak in the injectors somewhere...
 
Rokee44 said:
hmm so we pulled an o2 sensor failure code...but its the same one we got before I replaced them. I looked a little closer into the fuel pressure situation.. although it stays at 49 psi..after you turn the engine off it immediatly starts declining..and over a period of 4 mins it gets right down to 10 psi. anyone know if this is normal for a 98 to do this? or should I take that as a sign that ive got a leak in the injectors somewhere...
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Thats way too much leak down. Im not sure what the test is with a 98... but that doesnt sound right at all. In my 90 the anti-drain back valve (if thats even what its called) is in the pump. I think a faulty FPR (fuel pressure regulator) will also cause this. I doubt that the injectors would be leaking THAT much fuel without a much stronger smell.

Does the 98 have a vacuum line going to the FPR?? If so, test the pressure again while running, and remove the vacuum line from it and see what your reading is.
 
not too sure..its above the fuel tank, kinda akward to get at it... I do believe it does though. is there anyway of testing for a faulty FPR without gettin way back there? even though it runs like crap it still is my DD...so if ive got to drop the fuel tank I wouldnt mind havin all the replacement parts there and ready to go...
 
Pressure should not drop below 30 PSI for five minutes...put the pressure gauge in the fuel line with a Tee adapter...charge the line by starting motor. Shut off motor. Clamp off fuel line between the fuel rail and the Tee adapter. If pressure holds, you have a leaky injector or fuel rail leak.
 
alright. looks like a o-ring replacement kit is in the books for me. pressure held fine, only dropped to about 38 psi in the 5 min span... any quick tips on replacing the injector o-rings? anything else to look out for? thanks a lot Muad'Dib and McQue... helped a lot with this so far.
:cheers:
 
well out of frustration of that stupid not-so-quick fuel line disconnect, and finding out a new one was $20....I decided I no longer wanted to deal with it. so I cut it out and clamped a high pressure fuel line to the steel line and put my guage between it and the fuel rail. the pressure tested normal and only got down to about 40 psi after 5 mins...without clamping or anything...which seemed a little strange because I would've thought the test port should give me the same reading as this would. so I hooked my new fuel hose to the fuel rail and tested at the test port again..and sure enough it doesnt go down below 40 psi. (and it had dropped right down to like 20 before)...could there have been air getting in the quick disconnect and have lost pressure there?....i wouldnt have thought so at that kind of pressure but there is NO visible gas leak... could I have accidentally fixed my problem or am I missing something?
 
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so it didnt fix the backfires at all. however pressure and leakdown tests are now reading perfectly normal... so I am highly doubting this is a fuel problem... so what else can go wrong in a 98? map sensor is built into the manifold..(i think) TPS is not adjustable...but I suppose it couldve crapped out on me but theres no reason it would have... leak in the intake manifold (broken gasket possible?) Ive already checked the head bolts...theyre all tight. a clogged throttle body couldnt cause this much of a problem could it? this problem is starting to irritate me lol any further suggestions?
 
Possible timing chain issue. Take off your dist cap and turn the crank by hand. Use a breaker bar for this. They both should turn at the same time. If not it is time for a new timing chain.
 
Intermittent problems suck...here is what I'm thinking, but your game plan will probably change along the way as you learn new facts about the problem..

You can't ignore the 02 sensor failure code you got after replacing them unless it ghosted on you...was it a one time, non-reproducible failure?...ie; did you clear the code and it not come back?

Backfire can be lots of things... fuel starvation, timing (CPS, Camshaft PositionSensor), spark quality problems (Coil), or electrical problem related to wiring...

You need to be sure your 02 sensors and heater circuits are all functioning properly 100% before moving on to something else...it's the only clue OBDII has given you so far.

If you think they are working 100%, and you think that the fuel system is functioning 100%, I would start looking at timing/distributor circuit, (Distributor Cap & Rotor) spark, (Plugs, Wires) and engine wiring harness for chafed insulation, poor connections (grounds) Maybe you can get it to backfire by wiggling harness connections, sensor connections, flex the harness, injector connections, etc.
 
ok well I guess I will wait until the week just in case. monday I'll take it back to my family friends shop because he said hed throw in another O2 sensor incase I got a lemon on the ones we replaced..(did it on weds and the CEL came back on within 2 mins of driving...and it was another O2 sensor code that we pulled on friday). the CPS failed on me on a trail in the summer so ive already replaced that and did a full tuneup at the same time so im doubting that it would be the coil, CPS, or fuel starvation since i am now within spec... but i'll give it all a once-over to see...and good point maybe ill see if i can trigger the backfires myself....the thing is though its not reeally intermittent...i know exactly when its going to happen :S ive gotten to the point where I know that 4-10 houses down my street its going to go so i pull onto a side street out of heavy traffic and wait for it... then like I said its perfectly fine for the rest of the drive. but perhaps its a connection or leak somewhere that expands or something and has an effect at a certain temp? i dont know its weird... ill just check ALL connections then get into the timing stuff.. im considering ordering up a new intake/header gasket...this all started to happen a few weeks after i put in the new header so who knows...couldve gashed it on something thats causing a leak...would something like that have this much of an effect?
 
I'm doubting a vacuum leak would act that way...
Test your vacuum at the intake manifold...my 01 XJ idles at 16"hg and 20"hg at 2000 rpm....your family friends shop should have a vacuum gauge...you can buy them pretty cheap... I got a used one off E-bay for $4.00 plus $5.00 shipping...
 
ive got some air pressure guages lying around I can probably just throw one together and check it...is that valve on the side of the intake manifold where i would check for that? (the one that had broken off..see first post)... and im glad to hear that it probably isnt a manifold leak...lol had to uninstall/install 2 times because i couldnt get at the stupid bolts :P any other suggestions? I plan on gaining as much advice as possible and just make a list..then 2morrow I can just run through it all at once.. (it feels like -20 C (-5 F) outside at the moment and we just got almost 2 feet of snow...so im planning on a nice 2-3 hour shift in the garage and get as much done as possible.
 
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the vacuum pressure readings are as follows...
cold start - 17.5 in/hg
warm idle - around 15 in/hg
warm @ 2000 RPM - around 20 in/hg
this is a little lower than spec i believe but...not entirely convinced this is my problem... plus it was sputtering a little bit so that maay have lowered the pressure....(when the engine starts shuttering it drops to about 10 in/hg and the air filter sounds like a friggin tornado)
any ideas what my next step would be?
 
so if we recap the problem...
evap vac line repaired, fuel pressure tests good, vacuum test goods, connections look good...O2 Sensors swapped...
Is the 02 code gone and not come back?
 
yes all the way through...except no...the o2 did go away temporarily when sensors were swapped, but then CEL came back about 5 mins down the road... checked it out, O2 code again...so no, the o2 code did come back
 
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