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Discussion Starter · #1 ·
Ok, problem, intermitant problem.

I have serious lag in the acceleration from standstill, or low rev's. Not good at junctions or slow moving traffic. When the revs do kick in they go sky high even up to redline then drop just as quick. This is with a little touch on the accelerator, enough normally to get it 2000rpm.

Also when i am accelerating the temp gauge drops even if the car has been running for 20 mins plus.

I have done a full service, including air and oil filters, oil and sparks.

Has anyone come across this at all???

After i tried all i could think about i took it too the mechanic and he doesn't know.

Any help would be greatly appreciated.
 

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Thermostat and coolant temp sensors. If your cooling system guauge reads less than normal while driving, your thermostat is stuck in the OPEN position which means the engine will never get to operating temp let alone stay there. By doing so, the coolant temp sensor tells the DME that the engine isnt fully operatabe which will also have teh possibility of telling the o2 sensor to run in a loop until its at the correct temp which would mean its running rich and youre wasting gas, burning spark plugs, and the catalytic converter.

Id replace the thermostat and inspect/replace the cooling temp sensor(s) depending on what year and engine.
 

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Discussion Starter · #5 ·
Well its not an auto so i dont think its that.

Will have a look into the thermostat and coolant sensors, which is what i thought it was at first but nice to have some confirmation.
 

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ok, first things first. check the basics. take a fuel pressure reading and see what it does when the revs are increased. if possible, check the gasses coming out of the tailpipe. this will let you know if you are runing rich (possible coolant sensor issue).
the temp guage dipping may or may not be related, but check your fluid levels anyway.
does your mechanic have a power graphing meter?? if so, have him scope the throttle position sensor and look for a drop out or hashy reading. (if he doesn't know what a power graphing meter is, then i would suggest seeking out a mechanic that does)
also, check for corrosion and moisture around the sensor connections, and, as stated before, check your grounds. if your mechanic doesn't know how to do a voltage drop test the i would say definately seek out a new mechanic.
if the temp guage read in the middle when warmed up, take a reading of the hoses with an infra red temp scanner. compare this reading to specs (open @ 176 F).
also take a vacuum reading. since it is a 4 cyl, it may have a wiggle in the needle, but it should not be bouncy. i would expect to see 14"Hg at idle (minimum). this should dip down to almost 0 when the throttle is opened but stablize pretty quickly and hold steady.
if it is low, then you could have restrictions in the intake or exhaust, worn valves, worn timing chain/stretched chain, that sort if thing. without seeing this sort of info the mechanic would be guessing at best based upon his experience with the symptoms.
guessing is expensive.
best of luck, hope this helps.

drivinfaster
 

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Discussion Starter · #8 ·
ok, first things first. check the basics. take a fuel pressure reading and see what it does when the revs are increased. if possible, check the gasses coming out of the tailpipe. this will let you know if you are runing rich (possible coolant sensor issue).
the temp guage dipping may or may not be related, but check your fluid levels anyway.
does your mechanic have a power graphing meter?? if so, have him scope the throttle position sensor and look for a drop out or hashy reading. (if he doesn't know what a power graphing meter is, then i would suggest seeking out a mechanic that does)
also, check for corrosion and moisture around the sensor connections, and, as stated before, check your grounds. if your mechanic doesn't know how to do a voltage drop test the i would say definately seek out a new mechanic.
if the temp guage read in the middle when warmed up, take a reading of the hoses with an infra red temp scanner. compare this reading to specs (open @ 176 F).
also take a vacuum reading. since it is a 4 cyl, it may have a wiggle in the needle, but it should not be bouncy. i would expect to see 14"Hg at idle (minimum). this should dip down to almost 0 when the throttle is opened but stablize pretty quickly and hold steady.
if it is low, then you could have restrictions in the intake or exhaust, worn valves, worn timing chain/stretched chain, that sort if thing. without seeing this sort of info the mechanic would be guessing at best based upon his experience with the symptoms.
guessing is expensive.
best of luck, hope this helps.

drivinfaster
Excellent, will definately take your sugguestions to the mechanic and see what he comes up with.

If he doesnt know how to do them, i think i might just take it to a dealer. But will replace the thermostat first to see if that fixes the problem as it is a cheap enough thing to do. Thanks again
 
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