My car is suffering from a jerkiness when driving which I hope someone might be able me with.
Firstly it\'s not the 2,000 - 3,000 hesitation that I sometimes read about .This is slightly different.
When I come on or off the throttle I can feel a slight "stumble" from the car almost like the throttles are closing too fast.
Puzzled as to what it may be. The car runs perfectly well otherwise smooth idle, no smoke or water loss. It\'s had it\'s service recently so new oil, filter, fuel filter and plugs (problem was there before).
Changed the dash pot (as recommeded in the service manual) made no difference.
I have read about the TPS but have checked this and found no problems.
If anyone can offer any help I would be grateful.
Car details;
1996 UK Car
24,000 miles
Intake kit (Gruppe M Carbon Intake)
HKS SSQV Valve
I have removed the UIM and polished it (maybe something wrong gone here?)
Apart from that the car is as standard.
I seem to remember the problem started as I was driving to Portsmouth and I noticed the car was difficult to drive on part throttle in traffic.
Could a solenoid valve be faulty?
Anyone got any ideas?
Have posted this subject on the US forum as well, where it seems to be a common thing with most 3rd gens.
tps (throttle position sensor) prob needs adjusting
http://www.rx7club.com/showthread.php?t=170731
I had this when i forst got mine, its more like it feeling it wants to go off the throttle and its like the clutch is very jumpy. Mine seem to disapear once i\'d used a bit. I think sometimes its just saying it needs to be used and is just a character of the car.
I get it now and again like it feels very lumpy and i now have an uprated clutch. It disapears as quickly as it comes.
shaun
Sorry, just reread your thread. There is a damper on the front of the throttle body that decellerates the butterflies when you let off, maybe you need to raise that up a little to slow down the butterflies.
Shaun
Thanks guys,
You could be right, I don\'t get to drive the car a lot so I suppose it could be a bit grumpy with me!
Yep the damper is the dash pot, replaced it and have adjusted it to the specs in the service manual, maybe I\'ll try adjusting it some more to see if it works.
Tested the Throttle Position Sensor with a voltmeter and everythings ok.
Thanks
Andrew.
Ok, a bit to add to this one.
Adjusted the dash pot and checked the TPS again, thought it had made a difference but the problem still seems to be there.
I\'ve noticed that if I\'m in say third gear at 3-4,000 rpm and come off throttle the car does not slow down smoothly it kind of stumbles as the revs decrease. As the car slows down the effect gets worse.
If I press the clutch in the effect dissapears.
I\'m starting to wonder wether the intake kit is making the car run lean at low rpm\'s.
I do still have the original airbox, would just be a pain putting it back!
I have the exact same problem. Really annoying in slow traffic when you are on and off the throttle, the car can jump around a bit, and I fear it will damage the drivetrain. I have always thought it was one of two things:
Either a slight mis fueling at very low revs, clogged injectors perhaps.
Or, a problem with the drivetrain, maybe the diff is about to go!
Have had it on other old cars, where they have done a few miles, I often think the previous driver hasn\'t been smooth on and off the throttle and that is just how the car drives now. Let me know if you fix it.. ??
Read a couple of threads on RX7Club about a similar problem. It could be caused by the engine and transmission moving slightly under acceleration/decceleration.
I believe the FEED engine brace (and other makes) appear to help with this problem.
Also upgraded polyurethane engine mounts could help with this as well.
Not something I looking at doing right now, but if anyone has used these items on their car I would like some feed back.
Thanks again.
Quote from: shaunwilSorry, just reread your thread. There is a damper on the front of the throttle body that decellerates the butterflies when you let off, maybe you need to raise that up a little to slow down the butterflies.
Shaun
Andrew any update on this ??
I have looked at this damper and it does look a likely suspect.
But I also have the problem coming on the throttle. If I let off in traffic, 2nd or 3rd, then come back on the throttle as gently as poss, I will get a lurching/jumping for a second or two before smooth acceleration. It is really annoying, and I\'m sure it\'s damaging the drive train.
Can anyone help please ?? :2Mad
Hiya,
Sorry to say I haven\'t had any luck so far with this.
You\'re right it\'s a problem that makes you worry about snapping the transmission in half! It can sometimes be that bad.
The service guide has some interesting suggestions, but most of them seem to require the use of the diagnostic equipment that the service team use.
I was hoping someone from one of the RX7 Specialists might offer a solution to this common problem.
The best way I can describe it is as follows (see if you agree);
1. On acceleration there is a slight delay with the throttle of about 1-2 seconds and then the power comes in quickly. Also anything below 2,000 rpm results in very little torque, so the car wants to stall.
2. On deceleration the car starts to shudder below the 2,000 mark in 1st, 2nd, or 3rd gear. It\'s still there in 4th but just not as noticeable.
The delay makes me think it\'s something to do with the double throttle control maybe?
Damn why does the throttle on our car have to be so devilishly complicated. haha!
I could keep changing sensors like there\'s no tomorow, but that could be very expensive.
I understand the O2 sensor can wear out, been thinking about changing that (about £40).
Slightly off topic but relevent to this, when you check the engine codes can someone tell me where the engine check light is cause I haven\'t seen it yet! I need to know I\'m looking at the right place on the dashboard.
If I\'m feeling really brave I might let the Mazda garage look at, at least they have the technical equipment needed.
Thanxs.
I have the same problem, with freshly cleaned injectors, a freshly rebuilt engine, a brand new 02 sensor and brand new turbo and idle control solenoids.
Im pretty sure the problem is just slop in the drivetrain. My next line of offence is going to be changing my engine mounts - i used to have a similar problem on my old vauxhall nova (2.0 litre 16v turbo engine) and changing the engine mounts for uprated items cured the problem. Not sure if changing them out for standard items would have helped but i know it cured it changing them.
P.s my engine mounts are knackered on the rex. Have you checked yours?
No I haven\'t, what about an engine brace would that work as well as new engine mounts do you think ?
May well do. Im pretty convinced as i say that its slop in the drivetrain. I.e driving along, engine is loaded torsionally in one direction, you brake, which loads it in the other direction and the idle tries to compensate, which makes the engine jump the other way, which the idle then lifts right off because of, repeat process.
I.e the engine is twisting like its doing the twist again like it did last summer, which makes the car jerk like a mofo.
Someone should turn down the volume then..
Does the FD have the fuel pump resistor and relay like on the FC - this switches a resistor into the fuel pump circuit for idle, deceleration and light acceleration, as the pump does not need to feed as much fuel in these conditions. It could be a dodgy connector or something in that area that\'s causing the hesitation - maybe bad fuel flow causing the hiccups. On acceleration medium to strong throttle, the fuel pump gets full voltage, so the problem would dissappear.:3Confused
exact/similar problem on mine - Where is the TPS. ?
Have had this similar problem on a MK1 MR2 and it was the TPS.
I had something similar but very mild, and also found it would drop to correct smooth idle if clutched in from higher revs, but if you gave it a small blip it almost wanted to die... But found it was all caused by slack in the throttle cable, so I\'d come back on the throttle and it\'d pause a bit then hiccup forwards as the slack was taken up IYSWIM.
But I guess you\'ve checked this right? (pretty obvious)
If it was the O2 sensor then idle would also be dodgy as well as cruise. Can you reset the ECU\'s on these easily?
Found the TPS...... back of the inlet manifold near the top. Tweaked it lunch time and feeling a bit better. Although as mentioned above, I think some of mine is a slack throttle cable as well, which will be sorted later.
Checked the TPS the best I can with a volt meter. And was within the ranges specified in the guide.
I do have a new throttle cable as the insulation on the old one was cracking. Haven\'t fitted it yet. There is a little bit of slack in the travel but not sure if this would make a difference.
I am doing the service at the weekend and weather permitting will change the cable at the same time. Will update then if anyone\'s interested.
Quote from: Andrew HarperChecked the TPS the best I can with a volt meter. And was within the ranges specified in the guide.
I do have a new throttle cable as the insulation on the old one was cracking. Haven\'t fitted it yet. There is a little bit of slack in the travel but not sure if this would make a difference.
I am doing the service at the weekend and weather permitting will change the cable at the same time. Will update then if anyone\'s interested.
very interested..
Have to agree with Bobfish on this one and go with drivetrain slack as a possible cause.
Thanks to this thread you have identified the problem I have. Basically when I am trying to cruise with little or no throttle the car kangaroos. This also shows on the Apexi in two areas; firstly the injector duty cycle only ever shows 0.0% or 5.0% or above, never anything in between, secondly, the apexi map monitor shows that when using the accelerator the car is jumping between load site 2 and load site 0 (i.e. not going through load site 1).
This is bound to be because the throttle pot (throttle position sensor above) is not set correctly for low throttle positions. Thanks to your help, and by using the Apexi I should be able to set this really easily, especially as I can lob the Apexi out of the passenger door and look at it whilst fiddling under the bonnet. Basically, I need to get the throttle to sit at load site 0 when closed and open correctly through load site 1. Bingo!
ok. thanks andysmee. let us know how it goes.
Quote from: andysmeeThanks to this thread you have identified the problem I have. Basically when I am trying to cruise with little or no throttle the car kangaroos. This also shows on the Apexi in two areas; firstly the injector duty cycle only ever shows 0.0% or 5.0% or above, never anything in between, secondly, the apexi map monitor shows that when using the accelerator the car is jumping between load site 2 and load site 0 (i.e. not going through load site 1).
This is bound to be because the throttle pot (throttle position sensor above) is not set correctly for low throttle positions. Thanks to your help, and by using the Apexi I should be able to set this really easily, especially as I can lob the Apexi out of the passenger door and look at it whilst fiddling under the bonnet. Basically, I need to get the throttle to sit at load site 0 when closed and open correctly through load site 1. Bingo!
Now there a different way orf tackling it :Thumbs-up .
In truth I think its a bit of everything, I have tweaked my TPS, and tightened the throttle cable and it much better now. Whats left is as stated about transmissioin slack.
Update -
After fitting an engine torque damper I have to say the car is almost cured. The car is much more manageable in slow traffic and a noticably smoother gear change.
Get one !!
(http://i15.ebayimg.com/06/i/000/80/78/f8e8_1_b.JPG)
Is your air pump still connected ?
Before I fitted Apexi I disconnected mine and it was awfull in slow traffic - running rich at low revs.
Regards
Phil
I don\'t think it is no.
I am running single tub and full decat system.. But the car has always been a little lumpy since I first had it.
I\'m thinking that the engine mounts perhaps are finished..
Hello again,
Thanks Strange Days UK. Interesting that you say the damper almost cured the problem. Let me know how it goes over time.
I\'d read that if there\'s too much movement in the damper the bracket can crack the body work. But as I\'ve never seen a car with a damper fitted I can\'t verify this.
But I have thought about getting a damper for the car anyway.
Regards,
Andrew.