robadobadob 0 Posted April 17, 2012 Report Share Posted April 17, 2012 Ive got a '94 3 door VR6 that I'm prepping as a cheap track car for a bit of Summer trackday fun. The car was previously owned by a 60 plus lady that had owned it for 12 years or so, she's cared for it mechanically and it has heaps of history but I dont think its been driven very fast in all that time.I was doing a bit to it yesterday, replaced the nearside drive shaft (it was even clicking in a straight line!) and took it out for a test drive....on a private track, obviously.Throttle hard down in second up to 6k, shift to third and the engine got to around 5.5k and stopped accelerating so shifted to 5th and slowed down. I then did a 1st,2nd,3rd under hard acceleration again and this time it went happily to 6.5k in third.I havent so much as touched the engine and it is completely as it left the factory but has been serviced as required throughout its life but is there anything that could cause this or should I continue with the 'Italian tuneup' and see what happens.I'd just hate to show up to a trackday and find it missbehaves.Thanks in advance for any help. Link to post Share on other sites
oldmandon 1 Posted April 17, 2012 Report Share Posted April 17, 2012 Sounds as thought it was just a glitch...software was probably thinking what am I supposed to do at this RPM so hesitated, then it realised but you had throttled off so next time round it just performed as it should have. Wouldn’t worry about it too much and continue with your plans Link to post Share on other sites
robadobadob 0 Posted April 17, 2012 Author Report Share Posted April 17, 2012 Thanks for the quick reply, I think I'll stick some fresh plugs and leads on it too, just to make sure all is well. Link to post Share on other sites
oldmandon 1 Posted April 17, 2012 Report Share Posted April 17, 2012 Thanks for the quick reply' date=' I think I'll stick some fresh plugs and leads on it too, just to make sure all is well.[/quote']Never hurts to do that anyway, but if it’s got full service history they may be fine, just need a clean... Link to post Share on other sites
CALICO 130 Posted April 17, 2012 Report Share Posted April 17, 2012 It was possibly the MAF having a stroke at having all that air flowing through it.lol Link to post Share on other sites
robadobadob 0 Posted April 24, 2012 Author Report Share Posted April 24, 2012 Hmmmm this is still ongoing.Ive given the car a good service, fresh oil and filter, air filter, plugs and leads and the problem is still present.Ive started to use the car a bit to make sure all is well and put 110 miles on it yesterday and it ran well BUT if you try to rev it to the redline it hesitates and the revs slow down over 5k or so, the higher the gear, the worse it is but if you just cruise around all day then its fine and returns 25 mpg .Ive disconnected the MAF and it pops, bangs and generally runs worse than with it connected, also cleaned it which didnt make any difference. Disconnected the throttle switch and that made tickover high but the fault was still there. There is one thing, if you go from a closed throttle and accelerate, the first part of the throttle movement makes no difference and then it slightly snatches to catch up, then when lifting off it seems to do the same thing only in reverse!!!Feels like fuel starvation and I havent replaced the fuel filter but thats cheap enough to do unlike replacing the MAF (I was quoted £171+vat!!) so not sure where to go now.Could it be a blocked CAT? its a hell of a sight cheaper to deCAT it than replace the MAF, thats for sure!!Is there a cheaper MAF or are we stuck lashing out on a new Bosch one??? Link to post Share on other sites
Lukey. 381 Posted April 24, 2012 Report Share Posted April 24, 2012 ring your local TPS and see if they still do an exchange price for your old one, should take the price down loads if they still do Link to post Share on other sites
robadobadob 0 Posted April 24, 2012 Author Report Share Posted April 24, 2012 Hmmm I have tried them and the MAF was deleted in 2010 and not replaced!!Might try a 2nd hand one........... Link to post Share on other sites
michael5556 247 Posted April 24, 2012 Report Share Posted April 24, 2012 Maybe your throttle cable is getting stuck? Or try the throttle position sensor. Link to post Share on other sites
robadobadob 0 Posted April 24, 2012 Author Report Share Posted April 24, 2012 Throttle cable has been replaced but TPS is a good shout, I'll give that a go. Link to post Share on other sites
robadobadob 0 Posted April 30, 2012 Author Report Share Posted April 30, 2012 Ok, I finally got to the bottom of this one.Turns out it was a massive air leak between the AFM and the throttle body. The breather pipe that goes from the cam cover to the PCV valve near the throttle was practically in half so was letting in huge amounts of unmetered air hence the initial opening of the throttle did very little due to the AFM not seeing the increase in airflow and the missfire above 5k was due to very weak mixture at high revs!!!!Lovely and smooth now............................... Link to post Share on other sites
oldmandon 1 Posted April 30, 2012 Report Share Posted April 30, 2012 Well done on getting to the bottom of this....you must be a happy chappy now??!!! Link to post Share on other sites
robadobadob 0 Posted May 1, 2012 Author Report Share Posted May 1, 2012 I am indeed, just dropped it in to have the stainless exhaust fitted to celebrate!!!! Link to post Share on other sites
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