chris_stampe

My engine will cut out (usually after about 4500 rpms). I am wondering if this could be the 3800 rpm cutout, or if this is something else. I have another thread posted http://www.rx7forum.com/showthread.p...threadid=40563 with more details about the problem. If it is this 3800 hesitation is there anything i can do about it? When it cuts out there is an exhaust poping sound...should i get less restrictive exhaust (HEADERS!!)? I will eventually get them, but i am tight on cash. But if they would fix the problem i would definitly dish out the money for them. Thanks

Node

iTrader: (1)

The 3800RPM hesitation is from bad grounding of the ECU, it happens when the primary injectors lower there flowage and the primaries are supposed to kick on, but the ECU can't handle all the operations at once, so it sort of hesitates, and jumps I guess,
I think it is only on Series 4 (1986-1988) RX-7's.
And it can be fixed
I think I got that out right, I might had said something that wasn't right, but anyways here is a page on how to fix the hesitation, you have to solder and extra wire from a couple grounds on your ECU to your frame (grounded) or to your battery
http://home.earthlink.net/~burntoast/3700.html

HAILERS

http://home.earthlink.net/~burntoast/3700.html

Node

iTrader: (1)

delayed reaction?

chris_stampe

So im not quite sure if you think that that might be the problem or if you are just telling me how to fix it if i find out it is the problem. The thing is that the previous owner ditched the fuel injected system and put in a high flow carb setup for a turbo kit he had, but he took the turbo out--damn idiot. Anyways, im wondering if soldering extra ground wires might help me out. Im sick of loosing to my friends 3 gen eclipse!!! The bastard pulls ahead a few feet every time the damn engine cuts out!

HAILERS

I'm saying that I bought a used trashed out 87 and rebuilt the engine and was puzzled why the darn car ran not much faster than my 82. Found FC3SL.ORG on the web and the fix. Disregarded it, that only happens to other people. Wised up one day when I realized that my car would run fairly good after I disconnected the wiring harness at and around the ECU. Then after a week or so would revert back to its old ways. I pulled the connector at the boost sensor and spliced in a ground wire to the brown wire with a black stripe(pure black on newer cars). Put the other end on the water filler neck. I read .1 ohm at the brown wire with the black stripe. That wire, the brown wire with a black stripe is spliced into the ground wires for about six different sensors, so if you ground that one, chances are that you are improving grounds for the others. The others are the tps, atp sensor, water thermo sensor, air intake sensor, variable resistor etc. Get the idea? Some people say that did not help them and they added one at the tps, added a ground from the engine to chassis, added additonal gnds at the ECU grounds(darn good idea, I did that one too, even after I had no probs). Only takes about thirtyminutes or less to add on at the boost sensor. You really need to ohm out the ground to make sure its under .1ohm. Anything less sucks. Go for .0025. Might take a little longer than 30min.

RETed

Waitaminute, your car ha no stock fuel injection system???

Gee, I can't help you there...




-Ted

HAILERS

If you don't have fuel injection on your car after I wrote that long winded reply I'm gonna............... So anyway, if you have a carb, what is it and how does it run. Nah. You've got fuel injection. If you didn't you woulda said so in the original post. Cheez. I'm going out back and pull weeds in the yard and get something done.

chris_stampe

Yep, you heard me right, the previous owner put in a carb system in place of the old fuel injection. Now is there any way that grounding would help now or any other thing i could do to hopefully fix this engine cut out? Maybe you didnt write all that for nothing, cuz im sure someone has that problem. Thanks for the help

HAILERS

I don't see the grounds doing anything for your. Maybe someone else does. There must be a different fuel pump in there or they've put some kind of regulator b/t the carb and pump. I started down the carb route when I initialy had problems with my 87na(the ground prob with the secondary injector plug wires having been spliced on poorly due to previous owners FIRE). I have a Jay-Tech carb manifold for a six port motor that I used for a short period with a Holley. Its real purty and is for sale at a reasonable price. Manifold only. Cash up front, I've been reading some posts lately about theft on line. DARN, GOTTA LEARN HOW TO READ SOMEDAY. Have you checked the float levels??? No prob with the post. My fault.

chris_stampe

about the fuel pump. i can hear it ticking behind me. it gets quieter as i give it more gas, so maybe its making too much pressure? so if i understand you, you have a carb setup in your rx7 too? I havent checked the float levels. Its kinda hard to work on it cuz its so cold and I dont have a shop. If you have any suggestions though i might be able to take it into my friends shop and work on it for a few hours someday. Thanks for any suggestions

HAILERS

No carb anymore. I removed it when I saw that it was going to cause me more problems than I needed. I have to pass emissions once a year, so I figured I had to get the fuel injection up to par, so I switched back and fixed my problems. Once I did that I figured the FI was the way to go. I just know there are some scca racers out there that have a carb setup and maybe they'll give you a reply. No suggestions that would be of help here. Sorry 'bout that.

Scott 89t2

maybe it's still jetted for the turbo? if so it would just be way to rich on the top end. causing it not to rev.

the car would need a different fuel pump and reg. carbs run around 5psi and EFI runs at 40psi. I assume the guy changed it if he ever had it running. or did he have it running?

HAILERS

Probably has a Facet fuel pump. I wrote back to mention that if you have not already, put a post int the TECH section and label having something to do with the carb. There's gotta be tons of 1st gen people who run carbs. If its a Racing Beat intake its probably one of their modified HOLLEYS. Who knows. Have fun

Wicked7

The problem occours on the 89-91 as well as the seires 4 (86-88). Your most likely looking at a glitch in the ecu. As performing the extra ground does not help. But you might want to try. These cars including series 6 FDs also include the 3800 hesitation. So your only real solution to this would to get a stand alone ECU ie Haltech, Wolf3D, Motec, Ect.


Good Luck.

Scott 89t2

or a carb would get rid of it to, since there are no 2ndary injecotors.... LOL, try reading the whole post.

Wicked7

Ok ***, I was trying to correct what node said. Guess I should be more exlicit.

BTW, Carbs are garbage for daily driven rotarys. EFI is more efficent and runs better than a carb, thats why I said buy a standalone ECU. Can you program fuel maps with a carb? No way. Go to Puerto Rico if you want carb action on a rotary.

Felix Wankel

Can you change the A/F ratio on your FI car with a few bucks in jets? No.

Wicked7

IF it makes you feel better about having a carbed rotary shure. Weigh the costs of a carb conversion to a Haltech. I will have the haltech EFI and you will have your outdated carb. Both for the same cost. Which one would be better? Carb? I think not.

Felix Wankel

My carbed car is a 12A. Do I need a Haltech on it? NO.

Wicked7

Um I have a 2nd gen EFI. Do I need a carb on it? Are we talking about 1st gens here? Or does the thread starter need a carb? Or do you need a clue?

Felix Wankel

Or do you need to quit posting dumbass replies?

Scott 89t2

he already has a carb.... that's why I said read the whole post. he won't have a 3800 hesitation since he doesn't even have efi.