Helping a friend get his usdm 93 rx7 running. Reman engine. Emissions deleted. All new silicon hoses, fuel lines, plugs, battery, fuel dampener, injectors recently cleaned. Mostly stock except exhaust, intercooler, radiator. Modern air with adapter. TPS sensor cracked, but presumably wouldn’t prevent car from running (see below, ran rough and now nothing).

At first car ran rough, maybe on single rotor. Only stayed running with throttle and would die quickly. Installed new plugs. Accidentally hooked battery up reverse, which blew 120 amp. Replaced fuse. Now car turns over but doesn’t fire.

Any idea? Smoke tested, no vac leaks. Does hooking battery in reverse cause other problems? Relays? The fact that it would run rough before makes me think the battery in reverse did something else besides blow 120 amp fuse.

thanks!

 

Pull the plugs and smell them. Running on one rotor makes me think flooded. I would add oil to the housings and see if that helps.

 

appreciate it. Already added oil to housings before even attempting to start. Issue seems to be electrical.

 

Check engine light on at all? If yes, try to determine what codes are being thrown.

Are you getting spark at the leads to the plugs?

Check the Joint Box fuse box, especially the fuel pump related fuse.

 

not terribly familiar with these cars, but I imagine car would need to actually run to throw codes. Any case, not expecting codes to help much on a car this old.

 

The ecu stores codes. There are about 50 codes. Good to know what else might be contributing to your problem. Could be a combination of things, made worse by running current backwards through your system.

 

Will it run on starting fluid and have fuel and spark been verified again? Does it have a stock ECU and does the tach bounce when cranking?

 

Are you still on stock ECU or are you running something like a powerFC. Stock ECU does not like to run without the emissions stuff like Air pump etc.

 

stock ecu

 

stock ecu; I’ll try some fluid

 

May be soon time to check the:

EGI Main Relay (Yellow)
Fuel Pump Relay (Green)
Fuel Pump Speed Relay
EGI Fuse
B1 Fuse
Btn Fuse
And in the Joint Box (Interior foot well):
Engine Fuse (#4)
Fuel pump fuse (#14)
and weirdly,
the Room fuse (#3)

The fuses you can look at. I don't know how you check relays. We usually just swap in a spare. The relays are usually tricky to remove. Wiggle, but do not crush.

Physically inspect the entire starter/ignition harness for any obvious melted points/ fried grounds.

Check your coils for obvious fried connectors (front and back).

If the TPS is cracked I'd be concerned about moisture getting in there.

 

The stock ecu will throw all sorts of codes for an emissions delete and, very likely, put the car into 'limp mode".

Even more so if the sequential system for the turbos has also been deleted (which is common with an emissions delete exercise).

 

relays and fuses checked already.
verified getting spark.
getting voltage to fuel pump.
going to pressurize fuel system next.
also have a spare ecu to swap in case we fried the original when battery got hooked up reverse.

 

When you have the old ecu out. Take a look inside it to see if you can see any damage.

 

You're not going to get it to run on the stock ecu with the deleted items you have AND those mods. In the off chance you do get it to start, it will do exactly what you described and then never start again. You need an aftermarket ecu. Continuing to troubleshoot will yield nothing. You're chasing a ghost.

 

Seems extreme. So with basic bolt-ons the car will NEVER start again? I agree the car needs an aftermarket ecu, but it’s hardly heavily modded! Come on …

 

2 things.... its not going to work. You need an aftermarket ecu or to put everything back to stock.

 

Never run again if you continue with the stock ecu, is what he means, I think.

Updated software for aftermarket ecu, including Power FC, allows the ecu to adjust to the modifications it encounters when plugged in.

This is a boon to people who acquire a built car, but don't really know what all the prior owner(s) did to the car.

A large majority of owners give up on the stock ecu, and , unfortunately, the sequential turbo set-up, because how much can you continue to trust the 30+ year old circuit boards in the old ecu(s)?

Many shops will refuse to refurbish a stock set up, partly because of bitter experience with owners repeatedly coming back with some malfunction or other to complain about.

First shop I went to get my sequentials restored told me I was an idiot to buy the car as is and it would cost C$70,000 to straighten out (*).

And this was the locally recommended shop.

( * he was off by about $45,000)

 

You're foolish to argue with an established knowledge base that is trying to actively help instead of telling you to search and figure things out on your own. Your problems have eclipsed your mechanical knowledge and ability which is what led you here, folks are trying to prevent your inexperience form leading you to stupidity and engine failure.
The car is over 32 years old, and yes, even with those "basic mods" it needs an aftermarket ecu with tuning for more fuel to be "safe". So many of these grenaded back in the 90's and early 2000's from improper fuel tuning after folks installed a less restrictive intake, free flowing exhaust, and turned up the boost.

 

Apologies if I came across as argumentative. I still think it's an extreme position. Any case, I appreciate your input all the same. <3

 

If reality is an extreme position then you have many long days ahead interacting with an FD. Good luck lol

 

Whelp, car runs now, though rough as before. No doubt many long days ahead, but as I said before it’s extreme to say the car would NEVER run again. 🙂

 

I will also throw in 90% of the time I've seen people send injectors off to be cleaned they clog up or act up. You very likely have an injector or two not working properly. I do not recommend cleaning 30 year old stock injectors, you don't gain anything and most times it just causes very hard to troubleshoot problems.

Dale

 

Good to know, appreciate the input! Any idea what causes the high failure rate? Something with the type/quality of the FD injectors, or just age you think?

 

Hi RX-7 club, this is my car that sacklunch and I (and a few other friends) are trying to get running.

Dale do you suggest buying new OEM injectors? I did just get these back from RC injector cleaning. I don't know for sure how old these injectors are, as I've bought a few sets over the years from this forum. It's reasonable to assume they are 30+ years old. I had thought that if they flowed the correctly (admittedly per RC) they should be good to go. If that was an incorrect assumption, it gets added into the list!

I could add that I did have it "running" well enough to drive around the block about 15 years ago with the current configuration (Mazda ReMan, vac hoses replaced, emissions removed, K&N intakes, big SMIC, 3" turbo back exhaust with high-flow cat). Since then and now the car has been sitting in a garage, with the only changes being traded out injectors and fuel rails (both OEM), fast acting IAT (IIRC the DriftinJim unit), and whatever connections we may have had to reconnect from UIM removal. Getting back to a point where it will run and idle well enough to find out whatever else may need fixing is my goal for now.

In addition to the things listed previously, in the last week we have measured ~40 psi of fuel pressure and we removed each plug lead and have visible spark. We have not yet pulled error codes. I recall there are some codes that will result from emissions delete, but if the forum thinks that will be helpful we can share the stored codes.

We are currently seeing that the car will crank, but will not combust unless an unreasonable amount of throttle is applied; and it will not stay running without ongoing throttle. I have not see the tach move at all in this time we have been attempting to start. I recall the tach worked normally the last time the car 'ran'.

In general from here we are planning to pull the UIM again and look for something we may have hooked up wrong, low-buck compression check, and after that probably start testing wiring and sensors. I'm open to suggestions of any particular things to look for, I'm hoping I don't have to go pin by pin through the wiring harness, but that may be what has to happen eventually. I intend to buy a proper compression tester eventually, but did not think it was necessary to do right now. Open to correction if I'm wrong about that as well.

I am not in a hurry (obviously haha), so I'm happy to take my time to have the best chance of having a drivable car again.

Thanks everyone for your feedback so far .