Convertible is bogging down....
 

Hi all,
My 88 convertible is bogging down around 3000-4000 rpms. It even boggs down while going uphill on freeways in 4th gear at about 60mph. Here are my options:

1. replace the TPS...throttle position sensor
2. rebuild all injectors as they may be clogged and damaged

Any other thoughts out there? It just seem like the engine is not getting enough gas and it's cutting out/bogging down and unable to accelerate LIKE IT USE TOO. I can't even race around town. When I try to punch the gas, it just boggs down....... I will Lose a race every time.

thanks,

Aside from not racing around town, research 3800 rpm hesitation.

john ny

Not sure what you mean? Is there a thread around here already?

Hmm...normally I'd say limp mode. You don't happen to have an S5 engine in it, do you?

My vert used to bog down on hills, and it was because my cat was broken and clogging up, choking the engine.

Man, not my language...please clarify. It's just your normal 13B rotary, original but rebuilt back in like 95....

Interesting...thanks. Here are my options:

1. cat problem, exhaust
2. TPS
3. injectors

Should I just flip a coin to see what to tackle first........?

S5 (Series 5) is 89+ FC's, S4 (Series 4) is 86-88. You have an S4.

If your cat isn't rattling, then it probably isn't the issue, but maybe worth checking out anyway, as it's pretty easy to do. I just suggested that, as it puzzled me for a while, and I thought the rattling was just a piece of metal flapping around.

Can you believe this....

I was told by a Mazda mech. that the engine compression might be down. Rebuild the engine, etc....costing $6K....

I know we're in a recession....but come on...don't try to rip me off....

fff ^ you can get a fresh motor from atkins for like 2300 fuck a rebuild fuck mazda

p.s. a good thing to do is check your port actuators on your bottom intake... i kinda had the same problem on my vert... they winded up being frozen closed..

Yeah, I looked at the Atkins website today. I just really don't think it's that serious.
The car has plenty of get up and go..... It just bogs down when I punch the gas.

possible fouled plugs and/or bad wires

just a guess

Good idea. Did that, plugs were fouled up big time. I changed them and it runs alot better....but still bogs down a bit. I haven't changed the wires as they are pretty new.

I will have to look at the TPS or other areas.

Did you ever get to find out the Solution?

Well, I just wanted to let you know that the FC might be in Limp Mode.
Same thing Gringo Grande has posted here.

I have a 91' FC Vert and I ended up buying a used working Metering Oil Pump and a used working ECU.

The FC then came out of limp mode and never bogged once at all, and I can now Red-Line the shit out of this FC.

My bros...I'm not hip with some of the language here: FC in limp mode...come again? In laymans terms please.... sorry, don't hate on me.

I thought it was a clogged fuel filter....well I changed it out and it's NOT the problem.
:lol:

You have an S4 and they don't go into limp mode so that can't be your problem. Do a search on "3800 rpm hesitation" and see if this describes your problem.

In all honesty, if you do not understand what we are saying and you are going to be an RX7 owner, I would strongly suggest you do a search on those (or any term) you don't understand. The cars are over 20 years old and I'd venture that 99.9% of conceivable problems have been discussed and solved at one point in time on the boards.

What people tend to get frustrated about is the super common problems when a new owner obviously hasn't taken the time to search and you run the risk of getting some attitude. Just a warning. =)

I'll spoon feed you this time.
86-88 = S4 RX7
89-91 = S5 RX7

S4s used a mechanical MOP (Metering Oil Pump) which is near bullet proof and the S5's used an electronic MOP which has a history of going bad and taking out your ECU and putting your car in what is known as limp mode...it won't drive very well.

As you do not have an S5 this is not your issue and I would strongly suggest you take your car to a knowledgeable Rotary Shop NOT the dealership which doesn't know shit about out cars.

Good luck.

You can do your own compression test with a standard compression tester.
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Your 3800 hesitation is most likely a grounding issue or your pressure sensor is not functioning correctly. You can clean up all of your grounds (don't skip the one under the UIM (upper intake manifold), and see what type of results you get. If your car idles around 750 rpm then I doubt your TPS needs to be adjusted.

You could also have a vacuum leak, I would recommend swapping your vacuum lines with new one's and doing one at a time. You might be surprised what you find that has "popped loose", or has broken over time.

Got it. It's a weekend car that has basically sat for the past 6 months. There was a time when I ran great. I'll do some research.

Arron Cake has a bunch of great articles here.

http://www.aaroncake.net/rx-7/tech1.htm

You'll find articles on two things mentioned here including the port actuator and the grounding procedure.

You should do the grounding procedure first. It's easy and a 20 year old car will have corroded grounds (even a CA car) and those old computers (ECU) will not tolerate imperfect grounds. Bad grounds typically manifests as a ~3800 RPM hesitation.

Our vert's cat had clogged and really impacted acceleration but unlike Owl there was no rattling. It's easy to test, just remove the cat and go for a quick run. You'll piss off the neighborhood but if that's the problem you'll know right away. Rotaries love a free-flowing exhaust.

When I have a question I'll search first. The best way is to select Search in the grey bar at the top of the page then select Advanced Search.

Type what you're looking for in the Keyword(s) field and then select "2nd Generation Specific (1986-1991)" in the Search in Forum(s) list.

Two other places to check before posting a question is the FAQ which you'll find at the top of the 2nd Gen forum threads listed as "Frequently Asked Questions on the 2nd Generation RX-7 - FAQ for FC" and the "2nd Gen Archive" sub-forum in which you'll find almost universally useful how-to threads.

Good luck with your project.

Thanks VR...that was good reading and informative. thanks for the link

Believe it or not Gringo, there are a ton of people that get "frustrated" at attitudes like this. If you don't want to help then don't post. Simple really.

Thanks to vrracing for his helpful answer.

It does sound like your 5/6 ports Not activating.
they are most likely gummed up and preventing the 'get up and Go" they offer when they kick in.
try reading this,especially what Hailers has to say : https://www.rx7club.com/showthread.p...ort+activation
Btw: I punched in key word:port activation..and sec gen specific section) through SEARCH and got a whole boat load of threads on this topic.

It really sounds like 3800 rpm hesistation. There's threads on this every week or so for the last 8 years I've been on the forums! Super common, hence some of the comments.

As for your other solutions; TPS problem less likely. Injectors may need cleaning, and why not get them cleaned anyway? 19 bucks for flow and clean at WitchHunter Performance. That's not unreasonable for a 20+ year old car.

Either way, this has happened to me on 2 old NAs(normally aspirated, ie not turbo charged) I used to own. In my case adding an extra ground to the ECU fixed it. I did other grounding as well, but got the best results from this ECU grounding.

Honestly, just search. All the info is out there for you. If you have a problem then or don't understand, people are willing to help you out. But you should at least read the FAQ!