light throttle hesistations with lean symptoms
 

For the last few months my car has developed some hesitations during cruise situations. If I give it more than 1/3 throttle it generally smooths out but if I try to hold a steady rpm or try to accelerate slowly (to save gas) it keeps misfiring.

I recently installed an LC-1 with a G2 analog gauge and noticed that when the car is running fine my AFR's are around 14-15. As soon as the car starts to sputter the AFR's shoot all the way to 17-18 sometimes leaning all the way out on the gauge. Light throttle during highway cruises show 17-18 AFR's as well.

I did some research yesterday and saw that several people with similar problems had leaky injector grommets. I think that is a possibility with my secondaries because they didn't fit very snug initially but is there a way to check before I go pulling them out? I've heard of spraying carb cleaner and listening for idle changing but I would like to do some sort of pressure check and listen for leaks.

Any ideas guys?

Thanks,
~Ant

tps good? stock o2 sensor good?

TPS, was adjusted dead on back in december (still a possibility though), and 02 sensor has roughly 1,500 miles on it so its in good shape. Can the tps alone cause the car to cut fuel like that?

Thanks for the input arghx, you always give quick and helpful advice :icon_tup:

I've actually had this problem for like a year, if not the whole time I've had the car (2, 3 years? I forget). A solution would be nice, I always just blip the throttle though and keep on going. Did this just recently show up?

yea, I'd say it's been pretty recent. I used to be able to smoothly climb up in rpms to conserve gas and there was never any hesitation at all but now I'm having to use 1/4 throttle and up just to keep from all the hesitations.

Another thing I noticed today is the car goes very lean when even I boost slightly...almost like my secondaries aren't opening up or the computer isn't compensating for it. I'm running water injection set to come on at 1 psi right now to compensate for the high AFR's but I'd like to get to the bottum of this quickly so I can enjoy some real boost lol.

Still running rtek 1.7? something sounds strange...

I'm running rtek 2.1 and have had some problems with lean issues when slighly accellerating from cruise...

Did you ever find the problem? could possibly be the same thing...

I have the Rtek 2.1 with the latest firmware update.

Discovered something today...the problem doesn't exist for a few minutes while the car is cold. I did a light pull while the car was cold and when the secondaries came in the AFR's went rich. Several minutes later the hesitations kicked in and AFR's went back to the 18's and the car would hardly accelerate...any more ideas on what could cause that symptom?

Here's what it is doing...

View My Video

Any more ideas?

Are you using a simulated narrowband output to the ECU? I'll have to go check exactly how mine acts soon and fiddle with my SNB (which is not currently hooked up due to nasty issues I was having with it detailed in another thread).

I still have my original 02, installed the wideband further down on the DP.

check that the range on the Tps is good No shorts or such, then look for leaks i used to do hvac and i could buy a "smoke bomb" that would burn for 1,2 or 5 mins to find leaks id say get a can and light it in the can and place where the filter is to find any leaks

the smoke should be harmless to the engine

or use brake cleaner when the car is warmed up to find a spot

check all the rubber on the engine something could be split after the maf

I'm not very familiar with this 'smoke bomb' ur speaking of? I do have some brake cleaner that I will be trying. Do you think I should just remove my TMIC, put a pipe in its place and start spraying around suspicious leak points?

I've found sprays to be pretty useless. Get one of these:
http://www.boostpro.net/prodtester.html

But I've sealed up my intake pretty well with one of those and I still have this issue.

I'm starting to think it's electrical. Again I drove this morning to class and while the car was cold AFR's stayed at 14-14.7 no matter what gear, onced it warmed up it immediately stuttered and AFR's went to 16+

Is your pressure sensor still connected? Didn't you have that hose come off once before and cause a similar lean issue? Can't remember it's been a while since then.

if you go to an hvac store and ask for one they shouldn't be expensive at all it'll show any pin hole leaks no problem its not a common thing for cars but ive found it very handy

How's your fuel pump running? How's the wiring and voltages? How about a new fuel filter too?

Yup, I fixed that vacuum line as quickly as I could, surprisingly that wasn't the problem though :scratch:. It still occasionally goes stupid lean right when I boost?

I'm gonna give the fuel filter and possibly a TPS (if I can get a hold of one) this weekend :nod:

Can you believe a brand new TPS is $215 and up.....ridiculous!!

^about two years ago I got mine for under $200 from Ray Crowe at Malloy Mazda (forum vendor here). (703) 490-8170 , ask for Mazda parts, ask for Ray Crowe

Do you know what makes the TPS go bad? This will be my third one if I do end up purchasing one and that means I have to readjust it once again :icon_tdow. My idle has never been so silky smooth before so I'm hoping it isn't the TPS

I think the plunger design is inherently prone to wearing out/failing. It's basically late 70s technology and all the OEM's moved away from it in the 90s. They use the rotating "slider" type potentiometers. FD and all the 90s Hondas have that design for the TPS, they're much more reliable.

ok so here's your plunger style TPS which began in series 3 Rx-7 (GSL-SE). The Bosch L Jetronic systems at the time had a closed throttle switch and a WOT switch and used the rate of change of AFM voltage for throttle pump function.

https://www.rx7club.com/attachment.p...1&d=1267387724

Now here's your basic slider-type TPS, this is the Denso/Toyota design:

https://www.rx7club.com/attachment.p...1&d=1267387724
https://www.rx7club.com/attachment.p...1&d=1267387724

now here is the FD TPS design:

https://www.rx7club.com/attachment.p...1&d=1267387724

and this is the NSX TPS:

https://www.rx7club.com/attachment.p...1&d=1267387973

I think you should check the voltage sweep of your TPS with an analog (NOT digital) voltmeter to see if there are any open circuits.