rb20det cold start prob?? maybe my start signal?

[bmxer300zx]

this is a repost from the rb engine section i reposted it here in hope of a quicker response just because this forum sees more use then the rb section and i know alota 240sx guys have rb20 experiance anyway here is the post and pics lol.

i have an rb20det swapped into a 1992 toyota cressida.I have been workin on it since august its almost done all thats left is shorten the drive shaft and fab up a downpipe that will be a pain in my balls lol.Any how when i start it cold i have to pump the pedal and wait about a half a miute or longer to get it to start.once it runs and warms up it starts almost right up when i shut it down and restart. now the way the car is setup is its running off a 240sx relay box and the toyota harness is uncut .i did a lil research and am thinking its because i dont have a start signal goin to the ecu? ive searched a lil on it but dont quite get it no real clear write up on it and i dont wana f@#k up and fry my ecu. was wondering on how to get a signal to it I have had to many cross my fingers situations with the car and dont want another.also i gapped my plugs to 1.1 but i also read people putting them at 0.8 what would be the best for a near stock rb20det? anyways any help would be great thanks

[Hoffman5982]

I have the EXACT same problem with my sr20. Hopefully someone chimes in with some advice that might even work for me

[Khost26]

Same with my sr20... Id love to see what it is.

[240life]

In your situation you could run the start signal wire from the ecu to a toggle switch powered by the radio power wire. Use the toggle to trigger the power to the start signal on start up, then turn the toggle off.

[OutToWinPAHC]

I would get a good meter on all of your questionable connections and look for voltage drop on start up. could be carbon build up on a relay, bad solder connection, ETC. Meters don't lie

[bmxer300zx]

thanks for replies i will give the toggle switch a try this cressida has also seen a sr20det swapped into it and had the same prob at cold start up.also i did take a meter to everything as well and all looked good til i went to the idle air control valve and wasnt getting power.i got power to that now and it actually smoothed out a lil but the cold start up is still there . i think from what ive read on a lil more resarch that that could be my prob with the start signal.also just a quick ques on the spark plug thing is should i gap 1.1 or 0.8 on my engine im running nearly stock and have it gapped 1.1 but i keep getting a mixed feedback on searching old posts? again thanks for info

[J14cm7]

Last year when i did my sr20 swap i didnt wire the start signal up and had the exact same problem. I wired up the start signal and bam starts right up everytime no matter how cold it is.

[bmxer300zx]

alright ran a wire from the push start to pin number 43 thats my start signal it was a whopping 43 degrees out and it fired right up. idk if the other guys with the sr swaps have theirs wired but that def helped me .thanks for info

[240life]

alright ran a wire from the push start to pin number 43 thats my start signal it was a whopping 43 degrees out and it fired right up. idk if the other guys with the sr swaps have theirs wired but that def helped me .thanks for info

No problem Thats what we did with my friends SR powered cressida. The start signal wire has a tendency to break, and jumping it works in a pinch.

[bmxer300zx]

lol thats funny i read this then looked at ur location could u potentially be talking about bens old cressida cuz ur looking at it lol but thanks for the help im still shifting through a ton of problems but its getting closer to being done.now all i gota do is order about few hundred dollars in gauges shorten drive shaft and fab up a downpipe and hundreds of other odds and ends.also replace the diff it sucked to begin with plus ben kicked its a** to hell lol

[240life]

lol thats funny i read this then looked at ur location could u potentially be talking about bens old cressida cuz ur looking at it lol but thanks for the help im still shifting through a ton of problems but its getting closer to being done.now all i gota do is order about few hundred dollars in gauges shorten drive shaft and fab up a downpipe and hundreds of other odds and ends.also replace the diff it sucked to begin with plus ben kicked its a** to hell lol

Bwahahaha thats hillarious...Yup, I almost purchased it for my track slu* while im finishing the s13 that was in his driveway. That cressida needed a good home. Glad to see it got one. I am assumeing he never wired the start signal in it then based on this conversation, lol. I thought it was odd to see another cressy sporting Bronco II rims, and was going to ask if you purchased it up in Maine. Whats the plan for the differential? You get those rockers fixed?

[bmxer300zx]

lol indeed.as far as the wiring i started to use his and the sr and rb r a lil dif so wat i did was just ripped it out .ran all new wires soldered shrink wrapped so wiring is all new xept for the 240sx fuse box.actually redid the ront bumper and bought a grille for it ill post some update pics with that and engine all finished.rockers rrrrr ahhh.... alota fiberglass and other materials worth of work lol but the floorboards and door jams were solid didnt go to crazy they look 100 percent better though.the diff im still in search for going mkiii supra but having a hard time finding 1 may just go to ebay for that.its funny cuz i bought the car thinking the swap would be easy then after new engine & transmission mount,drive shft shortened 2 and half inches make a ridiculous downpipe, rewiring, body work,and the ka power steering bracket and sr20 pump rigged on it has took three times longer than expected lol

[Hoffman5982]

I love you guys...

Worked like a charm!!!
I had an old pc switch laying right beside me when reading this, so I grabbed it and went straight out to my car and wired it up. It turns out it was a reset switch so you have to old it to complete the 12v signal, which leads me to my next question:
Should I pick up another switch that keeps the connection on as long as Im running it? or will it be fine to leave as is which is me holding the button as I turn the key and then letting go, breaking the connection, when the car starts?

Thanks again for the help. Now I won't be late to class

[240life]

I love you guys...

Worked like a charm!!!
I had an old pc switch laying right beside me when reading this, so I grabbed it and went straight out to my car and wired it up. It turns out it was a reset switch so you have to old it to complete the 12v signal, which leads me to my next question:
Should I pick up another switch that keeps the connection on as long as Im running it? or will it be fine to leave as is which is me holding the button as I turn the key and then letting go, breaking the connection, when the car starts?

Thanks again for the help. Now I won't be late to class

Only have thew switch on as long as you are starting the vehicle or you will burn out the circuit, there is no need for you to leave it on.

[Hoffman5982]

Awesome. Thanks!

[rob912]

same problem clean or or get a new maf thats what solved my problem