n/a 88 sutters after 3800 rpm
 

well i bough an 8 gxl a week ago with 61 original miles on it, first dat the fuel pump took adump on me and the car staed sputtering after 3800 rpm , when i fixed the fuel pum the car finally started again but i still cant push it past 3800 rpm with out it sputtering hard and pretty much lossing most of its horse power, it feels like a fuel problem but, when im in nutrel i can rev it all the way up to red line without sputter or lag, u when in gear i can not open up WOT past 3800 rpm with out it sputteing and pretty much laggining out, can anyone please give me a little bit of help, thank you

Check the faq about the 3800 hesitation.

i couldnt find anything, do you have a link for me maybe?

"I have this hesitation whenever I accelerate right around 3500-4000 RPM:
The dreaded 3800 RPM hesitation is cause 90% of the time by poor ground connections between the engine, the battery, and the car. Clean or replace all the under hood ground connections. On 86 model year cars , replacing/regrounding the pressure sensor's ground wire has helped (do not re-ground a 87 or later model year). If there is still a problem after that, look at cleaning the fuel injectors and (on a N/A) that your 5th/6th ports are operating correctly."

ok i will try that first thing in the morning if it is decent enough outsid, im gonna test the actuaters tomorrow and check the grounds, one senor was off the car, the one by the intake filter the vacume line was disconnected ut that seemed to not celp at all, and also it wanna change the inline fuel filter, do you kno where i can locate it y the fire wall or is there only the one on the fuel pump?

To be honest, I'm not to sure about the fuel filter (I would imagine there is just the one on the pump). I never really had any problems with my t2, it sort of all went at once and the motor popped, so I don't have that much hands on with it. Just check the faq stickied at the top and do some searching.
-Eric

ok thanks alot man you were very helpfull i appreciate it

andre

No problem man, good luck getting the car running better.

well from what i've read about rx7's and rotary engines the secondary injectors open up at 3800 rpms, i dont know if this info will help you or not but if you are losing power after 3800 rpms you can be sure that it is most likely a fuel problem caused by something to do with the injectors and also i think its 4400 rpms that vdi is full open so see if you can get it up that high and if it does anything at all.

3800 for secondary injectors and Aux port activation. 5200ish for the VDI

first of all... we all make typos every once in a while but damn..... spell check!

my guess is you need new injectors. if you can do it yourself, good. if not, be prepared to shell out a good few hundred dollars. i would replace all 4 injectors, both fuel filters and the fuel lines. This will cost you maybe $200 but it is an important system to keep your car running. Make sure to clean up the ground points under the upper intake manifold and the bridge ground from the engine to the firewall while your at it.

May not fix the hesitation 100%, but it will certainly help.

sorry for the typos, well i bought the car a week agon and it only has 61,000 original miles on it witch means it had to be sitting for quite some time, and it ran for maybe a hour or so once i got it on the road, ful throttle and all and now, now it takes a dump on me every time i floor it and it hits in the 4,000 rpm range, so can you tell me where the secondary filter is> and the injectors are inside the motor if i am correct right?

I had this problem too. I reground the ECU, and the pressure sensor.

Also, is this car using the stock airbox? I noticed I had huge hesitation with an open air filter on (cone type w/ adapter), but when I went back to the stock airbox, it was way less, even almost non-existent.

Fuel pressure test might help. I bought a few pressure tester for about $30. Might want to check on that. Also, fuel filters aren't that expensive. To figure out where it is at, I would just go to Mazdatrix.com and look at the picture of the fuel filter and see if you see anything like that in the engine bay. :)

Are your Aux ports working? I know there are a couple tests you can do, i think they are in the FAQ. Not sure though.

Good luck. 61k isn't bad. I am at 180k :). 25k on the rebuild though.

yea this car must have been sitting for years i got it for only 900$, im gonna check most of the stuff out tomorrow , its not a hesitation its more like a huge power loss or a strain on the car like after getting around 4000rmp like it just starts to choke, i am hoping its just like a fuel prolem, it must be because when the fuel pump wentthe car was pulling pretty hard right before it, then after the new install it still was a huge hesitation, thank you for all the help guys, i couldnt get more than one reply on automtive forums

andre

You guys need to think a little harder about the symptoms described rather than just repeat the same old "it must be grounds" blah, blah. This is not a hesitation at 3800rpm, he clearly said he "cant push it past 3800 rpm without it sputtering hard".

It sounds very much like one of the secondary injector is firing intermittently or not at all. It could be a dirty, loose or disconnected electrical connector on one of the secondaries, or a failed injector. Take the connectors off both secondary injectors (the ones visable on the UIM) and see if they're cracked or broken, make sure both pins are secure in the connector and thoroughly clean them with degreaser or contact cleaner. Clean the injectors' pins too.

If the connectors look okay, measure the impedance across the terminals (should be 12-13ohm). If that's okay, put 12V across the pins of each injector and listen for them to click open. If one of them fails these tests it'll need replacing.

If they're good electrically, replace the connectors, go for a drive and see if the problem's still there.

like i said though, its a 20 year old car so the fuel lines, filters, and injectors need replacing. you may not have to replace the injectors if you dont have the money, but they certainly need to be cleaned. it doesnt hurt to clean the grounds and connections around the UIM.

the reason a stock air box seems to remedy the hesitation is because the engine leans out and does not require quite as much fuel. if something is keeping the right amount of fuel from being delivered then having "too much" air in the A/F ratio leans it out.

my wording isnt quite right but you get what I mean...

This advice is fine (except about needing new injectors) but it belongs in a thread about preventative maintenance, not this one. Filters and fuel lines will do nothing in this case, and the injectors should only be replaced if they've been tested and proven to be the cause of the problem.

That's not how AFM-equipped EFI systems work. If the airflow changes, the ECU responds accordingly with the required amount of fuel. Adding a pod filter will have no effect on AFR.

i couldnt find anything on there about an inline filter, im going to check it out today and check out the injectors if i can find them, does anyone know exacly how many grounds are on the uim?

well i found the injectors, not the secondary injectors would be the one on the passenger side? also could i check to see if thats the problem simply by pulling the clip off of it and taking it for a spin, today i put more injector cleaner in it and now it sputters a little faster lol. first is pulling harder now and after i get it out of the 3800-5000 rpm range it opens up again but going into second and third i cant get it past 5000 rpm the lag is just that bad, but if im half way or a little less pressed on the gas it will go up the rpms normaly

Note - I was having the 3800 hesitation and even hesitations before 3800 rpm in the 2500 range too along with that I am still having the problem of my car backfiring over and over over when i am decelling in gear and when I downshift, I did fix the hesitation problem today this is what I did. My car is s4 na.

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Hesitation wont be as bad because there is not as much gas being used therefore (maybe) the secondary injectors wont turn on , because they are not needed/turned on unless at wot(wide open throttle) when youre going through the 3800 rpm range.

I today cleaned all the grounds on my car pretty much with sandpaper , cleaned the connectors with electronic cleaner spray also.

I found none of that fixed the problem the problem but when I swapped my tps (throttle position sensor) with another one I have the hesitation completely went away, but the problem with backfiring is still exactly the same.

Im trying to figure out what my problem is thats causing the backfiring , I think the tps I have in now may be bad also just not as bad as the last one was went it stopped working.

The tps can make the car drive crappy if not set correctly but my settings have always been the same so I dont see why out of nowhere the settings would make a difference out of nowhere...thats why i think its the tps is bad. I plan on getting another good tps and getting an ohmeter to test all my tps and set the one I get used correctly (assuming the other 2 are junk).

Good luck with yours.


Edit - Also those injectors that are on teh passenger side that are on the intake manifold those are the secondary injectors ( at least they are on s4 na) and the primary injectors are located under the intake manifold on the fuel rail that has the pulsation dampener.

thanks im gonna look into that, was the tps hard to change?
this hesitation is erking me cause the car pulled hard until the fuel pump went, so it must be somthing to do with the fuel, the car hadnt been started when i bought it in over 2 years, and it had less than a quarter tank of gas in it, so im gonna check the injectors and get a full tune up, then do the tps if i have to, its so wierd because if im not at wot the rpms go up with little to no hesitation, and i am still trying to figure out if there is a secondary inline fuel filter and where its located, the only filter i have seen is the one on the fuel pump

From what I know every rx7 has an inline fuel filter located on the right (driverside) on/near the firewall basically looks like a little black cylinder with two lines on it 1 going up onto it , one coming off it and going down. Replace with new oem mazda part , cost about $40 new.

The tps is easy to change , it only a matter of taking off two bolts undoing the
connection on the harness and swapping the other on. (5mins -10 mins max) , cost about $20 for good used one, u can only use 89-92 tps on s5 and only s4 tps on 86-88. As long as its your year its usable, no matter if its turbo or n/a they both are the same, at least im pretty sure...anyone correct me if I am wrong.

can you explain what s4 and s5 mean and also do you have a pic of where the tps is, i am so rusty with these cars i havnt owned one in like 8 years

S4 1986-1988 model

S5 1989-1991 model

I dont have a pic of the tps but its not hard to find,its basically a black button thats on the front of the throttlebody that is held on with a mount with two bolts (either 12mm or 10mm cant remember)


Attached is a pic of where the tps is located on s4 , i dont know if its the same on s5 but should be similar.

The location of the injectors, as well as everything else, is shown in the Factory Service Manual. If you don't have the FSM, click here and download it in PDF format for free. The answers to many of your questions are in there, so read read it before posting. You'll get more help when it looks like you're not just sitting back waiting for answers. :)

No.

That's not going to help. Have you done anything I said yet? You clearly have a problem with the secondary injectors. Stop messing around and check them.

the two secondary injectors are clogged, now someone at this mechanic shop down the road said to mix a quart of home heating oil in the gas tank and it should unclogg them, has anyone ever heard of this? sounds ogus but you never know

Run away from that man...

Pull out all four injectors and have them professionally cleaned.

i think thats what im gonna do, where are the other two? n the direct opposite side? i thought i had found them before but i was wrong, it was only the secondary's i found

another thing, when i first got the car the boost sensor hose was not connected o the motor, but i connected it fist day, the thing is there is no T on the vaccum line leading
from the sensor to the vaccum switch, theres alot of stuff out of the engine ay such as the ac unit and the hoses that heat the inside of the car, witch makes me wonder why the cars actual temperature doesnt go up, the guage only will get up about a quarter inch does that mean i need a new thermostat?

i have every problem you just mentioned , my car does the same sluggish acceleration from 3800 and up , i got my secondaries tested and they were 78cc/30seconds at 40 psi the guy said they were fine , so im guessing that the hesitation is not from the injectors , also my car had a older thermostat and i replaced it , now it only goes up about a quarter too

talked to a rx7 specialist today he said it could be the injector resistor under the airbox?

Go back and read post #25, then do what I said! Questions like this will start to bug people soon.

The vacuum switch next to the MAP sensor is only fitted to autos. It needs to be teed into the MAP line so the torque converter lock-up works properly. Is yours an auto? Or has it been converted to manual?

That's normal operating temp on an S4 gauge. It's fine.

One of you has your number and/or units mixed up, or they were tested by pulsing them at a low duty cycle. Testing them at 40psi would also give about 5% more flow than the 36psi the injectors are factory-rated at.

Your 88 doesn't have one.

While you're at it, change your plugs and wires.

ITS a manual hasnt been converted, the air box has a small port maye an inch wide on the left side of the map sensor wich i have no clue what was ever conected to it, so you are saying the boost ssensor for my manual should just go straight to the engine with no t fitting for any other vaccum lines?

yes , there shouldnt be a T there , i looked at mine and it goes straight to the engine

okay well im just buying new ones off a guy on this forum tonight anyways , shop didnt even wanna clean mine when i called them back

also you can try cleaning you TPS , i heard it can be done with WD40?
im not sure about this though a friend of mine told me this , is it ture?

i just noticed today when i brought it out for a spin that it occasionally gets a real bad fuel cut, like if im in first and going real slow if i go to give it gas real fast it prety much sounds and feels like the car completly stalls out for a split second then comes right back on, im just going to buy two new secondary injectors and a new inline fuel filter, i get the injectors for 65 a peice so thats not gonna be that bad

i was looking on mazdatrix today at the bypass valves and stuff, and i noticed one of the wires in the pictures is on that is not connected to what ever its suposed to be connected to on the car its the black wire with the clip on it
http://i72.photobucket.com/albums/i162/Andre614/rx.jpg
can you tell me where it clips into and if this is what could be causeing my problems

anyone?

everyone i talked to told me to chek my fuel pump and fuel filters

well my fuel pump failed on me, thats when all of my problems started,

bump

You need to chill,
I had the same damn problem,major loss of power at 3800 bucking all kinds of shit.
I ground the pressure sensor wire and what do you know back to complete perfection so before you say its not the grounds,check your grounds!

You need to know what you're talking about before telling me to chill. The pressure sensor ground fix is only for 86 FC's like yours, not 88's like his.

yes , the ground trick dosent work for 88's , it even says in the writeups

i think its a maf or airpump thing i have same problem only but happened when i put a cone filter on the car....has something to do w/ maf, pressure sensor and my grounds as well ....

i also just put a cone filter too , but could this be possible because wouldnt this happen to everyone with a cone filter?

Keep in mind that 99% of people who put a pod filter on their FC have no problem with it.

i cheked the secondary injectors there fine i suspectsomthing with the fuel pump or filter or the fuel line, after i put the injectors back i tried stating it ait revs but when i give it gas it dies and every time i try to start it i smell gas and theres some fluid leaking i think its oil

Okay, got that one cleared up , took the cone filter off and put the stock air box back on , nothing changed, but i think i fixed the problem ... somewhat , theres a ground wire behind the intake i disconnected it and cleaned it and put it back i also wiggled around the injectors , went for a drive , went up past 4k like nothing , 2 hours earlier it wouldnt go past 4000 , so i think forsure our problem is the grounding and injectors

Your not allowed to say anything about grounds remember