98 civic vtec : slughish / idle issue
 

Hello honda-tech

I recently baugh my 98 civic hatch and im having trouble getting it over 95mph (maxed out).It starts getting really slugish once im over 75mph .Also when I have it in neutral and i rev the engine the rpm idles back and fourth . I cant tell at how many rpms its doing it at cluster doesnt have a rpm gauge. Im new to this forum so id really appreciate your help.

As far as what i have is a 1998civic hatchback with a D16y8 engine and a chipped ecu. I've only had the car for 2 days so i havnt really looked all into it.Let me know what other info u need to help me get rid of this dam annoying issue .keep it real any idea ,advice , or knowledge i would help me out a lot

Raiders!!!

Re: 98 civic vtec : slughish / idle issue
 

Start out with the basics man.. plugs wires cap rotor fuel filter etc. If you're still having problems let us know and we can spoon feed you all the information that's already on the forum that could be found with a simple search...

Re: 98 civic vtec : slughish / idle issue
 

Don't go changing wires and cap and all that crap without testing first... no need to just start throwing parts at it yet.

Check spark plug gap or buy new ones if there is a lot of carbon buildup (spark plugs are inexpensive)
Remove and clean the throttle body.
Remove and clean the IACV. https://honda-tech.com/acura-integra...valve-1575913/
Check air filter (replace if needed). Clean all ground wires at chassis points.
Replace PCV valve (located under intake) .. easier to do during oil change. D.I.Y ---- Garage Oil change w/ PCV valve replacement (D16Y7) - Civic Forumz - Honda Civic Forum
Inspect rotor and cap for any hairline cracks, melting or pitting.
Follow Ron's spark diagnoses guide: https://honda-tech.com/honda-civic-d...blems-2919450/

You also mentioned it has a chipped ECU. Try to find out more about it from the previous owner: why was it chipped and what does the chip control. Could've been improperly or needlessly done.

Re: 98 civic vtec : slughish / idle issue
 

I disagree. Tune up parts are never a waste of time/money.. and the OP's issue sounds very much like symptoms of ignition miss or clogged fuel filter.

Before worrying about the idle surge, correct your miss/hesitation first and proceed from there.

Back to what I said, start with tune-up components and if that does not solve your issue, then you can proceed with further diagnostics... let us kno the results

Re: 98 civic vtec : slughish / idle issue
 

I checked the the engine the other day and the plugs and wires are good so is the cap i checked some fuse they all seem to be in good shape . i did notice that the head gasket had some paste type of sealant . also there at 3 connetions loose that i cant identify where they go . the motor seems to be in good condition : vtec kicks in nice , no funny sounds , oil is good ...

Re: 98 civic vtec : slughish / idle issue
 

Few more thing i forgot to mention ... The ecu is a P28 im not sure that its chipped for neither is the owner .. Also i found a cut hose that is conneted to a nipple on the engine head located at the left corner firewall side

Re: 98 civic vtec : slughish / idle issue
 

U checked the wires how, with a multimeter? And did u just visually inspect the cap, rotor, plugs? Or?

What connections are loose? Can u post a picture?

Did u change the fuel filter? If you open the top cover of the ecu, you can identify if the ecu is chipped

I can send you a d16y8 basemap on a chip if we find that is the problem but ecu is typically diagnosed faulty by process of elimination of other components. I would highly recommend replacing the fuel filter. It's inexpensive and would definitely cause the issue you're experiencing.

Re: 98 civic vtec : slughish / idle issue
 

Alrite ... So this is where im at.

I was in LA for the weekend and i was doing some research and i also baught myself an OBD2 scanner .. Long story short my scanner doesnt want to communicate with my ECM.
*i checked every fuse
*i checked for power to the DLC
*i also checked every connection to the ECM everything seemed fine ..

Until i opened up the ECM
Sad to say i may have a problem ... Dont know if thats wut is contributing to my " loss of power problem ...

Re: 98 civic vtec : slughish / idle issue
 

https://cimg6.ibsrv.net/gimg/honda-t...407f8e2eb0.png


Im not sure what happen but i think i might need another ECM ... The thing is that this ECM might be chipped from what i know .

Re: 98 civic vtec : slughish / idle issue
 

First off, your obd2 scanner won't communicate because it's an obd1 ecu. Obd2 car but using obd1 ecu - it won't communicate with a scanner via the obd2 port.

And yeah that ecu is fried, better start look for another ecu. I'm willing to bet my life savings that's your issue. Honestly I'm surprised it even runs, I've seen plenty of fried ecus and usually they don't run the car at all.

Did u buy the car with these symptoms, or what led up to this issue?

Re: 98 civic vtec : slughish / idle issue
 

Well that explains why i cant get any codes .im glad i found 1 more issue to fix .now my question ?

Since im going to go find another ECM which one ,would be the right one to use ?

Re: 98 civic vtec : slughish / idle issue
 

When it rains it pours, Q31. Just restumbled across this reading up at xenocron. And just posted in the 93 civic jdm D15B thread with the exact same issue.

If the plugs are reversed (same plug style/type common error) it will blow that transistor and also prevent the car from running or I guess run very poorly.

You have your purge solenoid plug plugged into your IAT and vice versa.

Re: 98 civic vtec : slughish / idle issue
 

I baught the car like this ... Its a good car im sure this just dirty parts ,worn gasket , and parts not connected right

Re: 98 civic vtec : slughish / idle issue
 

You can buy that transistor at xenocron.com

Re: 98 civic vtec : slughish / idle issue
 

Sorry for asking this but what is an IAT sensor

Re: 98 civic vtec : slughish / idle issue
 

Intake Air Temperature I believe.

Re: 98 civic vtec : slughish / idle issue
 

How can you tell if its chipped ? Can you show me ?

Re: 98 civic vtec : slughish / idle issue
 

After a good night's sleep, something occurred to me.

Before you just go switching plugs around, you need to test wires on the plug to pins on the ecu.

This is why, when the plugs were plugged in, it popped the transistor and whomever did it may have swapped the plugs to be proper.

Your plugs could be correct now just your transistor is popped so the ECU is missing vital information.

As for chipped ECU they add chips and hardware to the area in red, if done properly, usually add zif sockets then the chips so you can swap chips. See the pics below for location:

Attachment 393987
Attachment 393988

Re: 98 civic vtec : slughish / idle issue
 

https://cimg9.ibsrv.net/gimg/honda-t...54ebbb5732.png


That doea make some sence im gonna check it and take some pics during my lunch break ... I took this pic yesterday but i forgot to post ...<br/>What is this extra harnest for ? And is it affecting the ecu being that maybe this ia what pooped the tansistor ?

Re: 98 civic vtec : slughish / idle issue
 

I'm not trying to be a nit-picking dick but, NGK or Prestolite wires are between $70-100. If, the current wires aren't the issue than that's money pissed away. I understand new wires, cap, rotor and plugs should maximize spark but, but may be negligible at best if the current parts are in good shape.

Re: 98 civic vtec : slughish / idle issue
 

Ok i found the cause of my issue ...

So i was doing some more research on the ecu and its not really idling .. Whatbis happening is that the chip installed in the ecu is programmed wit a 2-step launch ... So when i rev it stays at a rpm limit

But im gonna buy a OBD2 ecu so i can read what is causing my CEL to go off ..other than that im gonna fix the Q31 resistor and keep the chipped ecu ... Id say problem solved

Re: 98 civic vtec : slughish / idle issue
 

Just a heads up, sometimes the damage is beyond the transistor when they fry up like that...

Re: 98 civic vtec : slughish / idle issue
 

Yes i understand that im not saying its fixed i still have a lot of work on this car .... But at least i know what was causing my car to act that way ...

On a different issue now .. I need help figuring out my air intake cuz it has plugs missing ... Ill put up another post for that later

Re: 98 civic vtec : slughish / idle issue
 

What else should i check or look for just to be on the safe side

Re: 98 civic vtec : slughish / idle issue
 

Really overall, visually you may not see much if anything out of the ordinary. Unless it burnt traces right off the board, you really won't know if there is additional damage without replacing the transistor and trying the ECU out.

Things like trace separation can happen and won't be visually detectable.

I sort of doubt the PCB boards are multi level but if they are, you have no way of detecting problems with lower level traces, especially not with just the human eye.